21557306800 has 30 divisors (see below), whose sum is σ = 51791430548. Its totient is φ = 8622922560.

The previous prime is 21557306791. The next prime is 21557306833. The reversal of 21557306800 is 860375512.

It is a self number, because there is not a number n which added to its sum of digits gives 21557306800.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 26946234 + ... + 26947033.

Almost surely, 2^21557306800 is an apocalyptic number.

21557306800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21557306800 is an abundant number, since it is smaller than the sum of its proper divisors (30234123748).

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

21557306800 is a wasteful number, since it uses less digits than its factorization.

21557306800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53893285 (or 53893274 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21557306800 in words is "twenty-one billion, five hundred fifty-seven million, three hundred six thousand, eight hundred".