21221551026536 has 64 divisors (see below), whose sum is σ = 46052956377600. Its totient is φ = 8979322480128.

The previous prime is 21221551026509. The next prime is 21221551026539. The reversal of 21221551026536 is 63562015512212.

It is a junction number, because it is equal to n+sod(n) for n = 21221551026493 and 21221551026502.

It is not an unprimeable number, because it can be changed into a prime (21221551026539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85139306 + ... + 85388198.

It is an arithmetic number, because the mean of its divisors is an integer number (719577443400).

Almost surely, 2^{21221551026536} is an apocalyptic number.

It is an amenable number.

21221551026536 is an abundant number, since it is smaller than the sum of its proper divisors (24831405351064).

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

21221551026536 is a wasteful number, since it uses less digits than its factorization.

21221551026536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268258 (or 268254 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 41.

Adding to 21221551026536 its reverse (63562015512212), we get a palindrome (84783566538748).

The spelling of 21221551026536 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred fifty-one million, twenty-six thousand, five hundred thirty-six".