21637968665056 has 12 divisors (see below), whose sum is σ = 42599750809392. Its totient is φ = 10818984332512.

The previous prime is 21637968665039. The next prime is 21637968665057. The reversal of 21637968665056 is 65056686973612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21637968665057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 338093260360 + ... + 338093260423.

It is an arithmetic number, because the mean of its divisors is an integer number (3549979234116).

Almost surely, 2^{21637968665056} is an apocalyptic number.

It is an amenable number.

21637968665056 is a deficient number, since it is larger than the sum of its proper divisors (20961782144336).

21637968665056 is an equidigital number, since it uses as much as digits as its factorization.

21637968665056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676186520793 (or 676186520785 counting only the distinct ones).

The product of its (nonzero) digits is 587865600, while the sum is 70.

The spelling of 21637968665056 in words is "twenty-one trillion, six hundred thirty-seven billion, nine hundred sixty-eight million, six hundred sixty-five thousand, fifty-six".