## 79

As we slide into a US holiday weekend — leading to Labor Day, the first Monday in September, this year on the 2nd — my birthday (on the 6th) looms as well. Coming up is a prime-th birthday, the 79th, an auspicious number to my mind, just one short of the 80th, which many view (like the similarly vigesimal 20th, 40th, and 60th) as a landmark birthday, in this case the gateway into old age. But for the moment I’m prime, baby.

Labor Day and my birthday. The year I was born, 1940, Labor Day was on the 2nd, as it is this year. In 1941, on the 1st (as early as it gets — too soon); in 1942, on the 7th (as late as it gets — too late); and then in 1943, on the nose on my birthday (just right).

Next Labor Day birthday: 2021, which I might even achieve.

The prime number 79. Number theorists are given to devising all sorts of arcane subclasses of whole numbers, especially of prime numbers, and then studying the properties of these subclasses. Understanding most of this work requires pretty heavy background in one or another subfield of mathematics, but a few are accessible to the average person (from the Wikipedia page on the number 79).

— 79 is a cousin prime with 83 and a sexy prime with 73. Cousin primes are prime numbers that differ by 4. Compare this with twin primes, pairs of prime numbers that differ by 2, and sexy primes, pairs of prime numbers that differ by 6 (note the pun on sex referring to sexual activity vs. the Latin root sex(t)- ‘six’, as in English sextet).

— 79 is an emirp, because the reverse of 79, 97, is also a prime (note palindrome).

— 79 is a right-truncatable prime, because when the last digit (9) is removed, the remaining number (7) is still prime.

79 is also a fortunate prime, a Gaussian prime, a happy prime, a Higgs prime, a Pillai prime, a permutable prime, and a regular prime, though the definitions of these would take us far out into the number-theoretic weeds.

Other notable 79s. Just three of a number of possibilities.

— 79 is the atomic number of the chemical element gold (Au), so this is my golden birthday:

(#1) Digital art by Serge Averbukh

— Mount Vesuvius famously and disastrously erupted in AD / CE 79; cross me and I will spew molten lava on you:

(#2) John Martin’s Destruction of Pompeii and Herculaneum (c. 1821)

— #79 in the Denson Sacred Harp (1991 edition) is (one of the hymns known by the name) “The Old Ship of Zion”, a rousing “Oh joy, I am about to die!” song — a sentiment I am at the moment not willing to affirm whole-heartedly (though the song is fun to sing; well, I like shouting songs):

(#3) From The Makers of the Sacred Harp by D. Warren Steel and Richard H. Hulan, 2010: words from Bryan, Songster’s Companion, 1837, altered; music from Thomas W. Carter in The Sacred Harp, 1844

A historic recording of the song:

(#4) Allison’s Sacred Harp Singers, “Old Ship of Zion”, on the album  Heaven’s My Home (recorded 1927-28)

And a recent singing:

(#5) Sixth Ireland Sacred Harp Convention (2016), SH79 “The Old Ship of Zion”

The history of the tune and the words is quite complex. The Denson book has a related song, SH388 “The Happy Sailor”, which in turn is related to a very popular African-American spiritual “The Old Ship of Zion”.

The SH on my future. Looking forward just one year, I’ll be facing more musical welcomings of death:

And if to eighty we arrive
We’d rather sigh and groan than live

This from the text of two SH songs I posted about on 2/13/17 on “Our allotted span”, Mortality SH50t and  Exit SH181. And note my memorial posting for Marian Bush on 4/17/16. Marian took up shapenote singing, with the Palo Alto group, when she was roughly 80, and often chose one of these songs to lead, with gusto. (She continued singing until close to her 100th birthday; the Palo Alto group now holds an annual memorial singing for her, at the end of August — just last Sunday, in fact.)

### 3 Responses to “79”

1. kenru Says:

This post just makes me all the more primed for my next birthday in 2020…although I don’t want to rush it.

2. Robert Coren Says:

The winter of 2017-18 was one of the relatively rare periods when my husband John and I were both in our primes (79 and 71, respectively). The next such pairing is 97 and 89, which strikes me as not impossible but unlikely.