21507863520 has 192 divisors, whose sum is σ = 79594389504. Its totient is φ = 4812933120.

The previous prime is 21507863513. The next prime is 21507863521. The reversal of 21507863520 is 2536870512.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507863521) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 88032 + ... + 225311.

It is an arithmetic number, because the mean of its divisors is an integer number (414554112).

Almost surely, 2^21507863520 is an apocalyptic number.

21507863520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21507863520 is an abundant number, since it is smaller than the sum of its proper divisors (58086525984).

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

21507863520 is a wasteful number, since it uses less digits than its factorization.

21507863520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313385 (or 313377 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 39.

The spelling of 21507863520 in words is "twenty-one billion, five hundred seven million, eight hundred sixty-three thousand, five hundred twenty".