21358439664 has 20 divisors (see below), whose sum is σ = 55175969256. Its totient is φ = 7119479872.

The previous prime is 21358439539. The next prime is 21358439681. The reversal of 21358439664 is 46693485312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 222483699 + ... + 222483794.

Almost surely, 2^21358439664 is an apocalyptic number.

21358439664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21358439664 is an abundant number, since it is smaller than the sum of its proper divisors (33817529592).

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

21358439664 is a wasteful number, since it uses less digits than its factorization.

21358439664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444967504 (or 444967498 counting only the distinct ones).

The product of its digits is 3732480, while the sum is 51.

The spelling of 21358439664 in words is "twenty-one billion, three hundred fifty-eight million, four hundred thirty-nine thousand, six hundred sixty-four".