21556715400 has 144 divisors (see below), whose sum is σ = 78976038960. Its totient is φ = 5225865600.

The previous prime is 21556715371. The next prime is 21556715443. The reversal of 21556715400 is 451765512.

21556715400 is a `hidden beast` number, since 2 + 1 + 55 + 67 + 1 + 540 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 524562 + ... + 564161.

It is an arithmetic number, because the mean of its divisors is an integer number (548444715).

Almost surely, 2^21556715400 is an apocalyptic number.

21556715400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21556715400 is an abundant number, since it is smaller than the sum of its proper divisors (57419323560).

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

21556715400 is a wasteful number, since it uses less digits than its factorization.

21556715400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088756 (or 1088744 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 36.

The spelling of 21556715400 in words is "twenty-one billion, five hundred fifty-six million, seven hundred fifteen thousand, four hundred".