645

Properties by base:

More about this number at Positiv Integers and Number Empire.

The number is not a prime.

Its 3 (3 unique) factors are:
3
5
43

Its 8 divisors are:
1
3
5
15
43
129
215
645
Its aliquote sum is:
411
makeing it a deficient number.

As Unicode codepoint (since version 1.1) this number represents this character:ʅ LATIN SMALL LETTER SQUAT REVERSED ESH in IPA_Ext (Source: https://ucdapi.org/unicode/latest/codepoint/dec/645); HTML: ʅ

In the work of Johann Sebastian Bach BWV 645 is Wachet auf, ruft uns die Stimme (à 2 Clav. et Ped.)

The number appears at position 1978 of the decimal digits of π surrounded by
5757396241389086583264599581339047802759009 Source: The Pi-Search Page

Computations done with Math::BigInt 1.999811 and Math::Pari 2.030523 based on PARI/GP 2.11.3 (elapsed: 985.934ms; cpu: 82.4100000000001ms)