21097692864 has 70 divisors (see below), whose sum is σ = 62540186324. Its totient is φ = 7032562560.

The previous prime is 21097692841. The next prime is 21097692871. The reversal of 21097692864 is 46829679012.

21097692864 is a `hidden beast` number, since 210 + 97 + 69 + 286 + 4 = 666.

It is a super-2 number, since 2×21097692864² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 21097692864.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2029702 + ... + 2040069.

Almost surely, 2^21097692864 is an apocalyptic number.

21097692864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21097692864 is an abundant number, since it is smaller than the sum of its proper divisors (41442493460).

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

21097692864 is an equidigital number, since it uses as much as digits as its factorization.

21097692864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4069795 (or 4069776 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 54.

The spelling of 21097692864 in words is "twenty-one billion, ninety-seven million, six hundred ninety-two thousand, eight hundred sixty-four".