21696668544 has 64 divisors (see below), whose sum is σ = 58071847680. Its totient is φ = 7176998400.

The previous prime is 21696668533. The next prime is 21696668549. The reversal of 21696668544 is 44586669612.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21696668549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165352 + ... + 265959.

It is an arithmetic number, because the mean of its divisors is an integer number (907372620).

Almost surely, 2^21696668544 is an apocalyptic number.

21696668544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21696668544 is an abundant number, since it is smaller than the sum of its proper divisors (36375179136).

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

21696668544 is a wasteful number, since it uses less digits than its factorization.

21696668544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431459 (or 431447 counting only the distinct ones).

The product of its digits is 14929920, while the sum is 57.

The spelling of 21696668544 in words is "twenty-one billion, six hundred ninety-six million, six hundred sixty-eight thousand, five hundred forty-four".