21364395520 has 80 divisors (see below), whose sum is σ = 55164906720. Its totient is φ = 7888379904.

The previous prime is 21364395421. The next prime is 21364395523. The reversal of 21364395520 is 2559346312.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364395523) 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, 287700 + ... + 354259.

It is an arithmetic number, because the mean of its divisors is an integer number (689561334).

Almost surely, 2^21364395520 is an apocalyptic number.

21364395520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21364395520 is an abundant number, since it is smaller than the sum of its proper divisors (33800511200).

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

21364395520 is an equidigital number, since it uses as much as digits as its factorization.

21364395520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641995 (or 641979 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 40.

The spelling of 21364395520 in words is "twenty-one billion, three hundred sixty-four million, three hundred ninety-five thousand, five hundred twenty".