21697744128 has 72 divisors (see below), whose sum is σ = 57772024800. Its totient is φ = 7229528064.

The previous prime is 21697744091. The next prime is 21697744177. The reversal of 21697744128 is 82144779612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2498578 + ... + 2507246.

Almost surely, 2^21697744128 is an apocalyptic number.

It is an amenable number.

21697744128 is an abundant number, since it is smaller than the sum of its proper divisors (36074280672).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21697744128 is an equidigital number, since it uses as much as digits as its factorization.

21697744128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11947 (or 11933 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 51.

The spelling of 21697744128 in words is "twenty-one billion, six hundred ninety-seven million, seven hundred forty-four thousand, one hundred twenty-eight".