21154663520 has 24 divisors (see below), whose sum is σ = 49977892944. Its totient is φ = 8461865344.

The previous prime is 21154663493. The next prime is 21154663573. The reversal of 21154663520 is 2536645112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66108164 + ... + 66108483.

It is an arithmetic number, because the mean of its divisors is an integer number (2082412206).

Almost surely, 2^21154663520 is an apocalyptic number.

21154663520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21154663520 is an abundant number, since it is smaller than the sum of its proper divisors (28823229424).

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

21154663520 is a wasteful number, since it uses less digits than its factorization.

21154663520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132216662 (or 132216654 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21154663520 in words is "twenty-one billion, one hundred fifty-four million, six hundred sixty-three thousand, five hundred twenty".