21221252420524 has 24 divisors (see below), whose sum is σ = 40010910464448. Its totient is φ = 9790258070400.

The previous prime is 21221252420513. The next prime is 21221252420593. The reversal of 21221252420524 is 42502425212212.

It is a self number, because there is not a number n which added to its sum of digits gives 21221252420524.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86670817 + ... + 86915320.

It is an arithmetic number, because the mean of its divisors is an integer number (1667121269352).

Almost surely, 2^{21221252420524} is an apocalyptic number.

It is an amenable number.

21221252420524 is a deficient number, since it is larger than the sum of its proper divisors (18789658043924).

21221252420524 is a wasteful number, since it uses less digits than its factorization.

21221252420524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173588505 (or 173588503 counting only the distinct ones).

The product of its (nonzero) digits is 51200, while the sum is 34.

Adding to 21221252420524 its reverse (42502425212212), we get a palindrome (63723677632736).

The spelling of 21221252420524 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred fifty-two million, four hundred twenty thousand, five hundred twenty-four".