21621531255064 has 16 divisors (see below), whose sum is σ = 43658861188320. Its totient is φ = 9979168271520.

The previous prime is 21621531255043. The next prime is 21621531255097. The reversal of 21621531255064 is 46055213512612.

It is a super-2 number, since 2×21621531255064² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21621531255064.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 103949669392 + ... + 103949669599.

It is an arithmetic number, because the mean of its divisors is an integer number (2728678824270).

Almost surely, 2^{21621531255064} is an apocalyptic number.

It is an amenable number.

21621531255064 is an abundant number, since it is smaller than the sum of its proper divisors (22037329933256).

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

21621531255064 is a wasteful number, since it uses less digits than its factorization.

21621531255064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207899339010 (or 207899339006 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 43.

Adding to 21621531255064 its reverse (46055213512612), we get a palindrome (67676744767676).

The spelling of 21621531255064 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred thirty-one million, two hundred fifty-five thousand, sixty-four".