21320621536 has 48 divisors (see below), whose sum is σ = 44466117696. Its totient is φ = 10028261376.

The previous prime is 21320621521. The next prime is 21320621537. The reversal of 21320621536 is 63512602312.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21320621498 and 21320621507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320621537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1235560 + ... + 1252696.

It is an arithmetic number, because the mean of its divisors is an integer number (926377452).

Almost surely, 2^21320621536 is an apocalyptic number.

It is an amenable number.

21320621536 is an abundant number, since it is smaller than the sum of its proper divisors (23145496160).

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

21320621536 is a wasteful number, since it uses less digits than its factorization.

21320621536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19451 (or 19443 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

The spelling of 21320621536 in words is "twenty-one billion, three hundred twenty million, six hundred twenty-one thousand, five hundred thirty-six".