21556814400 has 1008 divisors, whose sum is σ = 89561017728. Its totient is φ = 4866048000.

The previous prime is 21556814369. The next prime is 21556814429. The reversal of 21556814400 is 441865512.

It is a happy number.

21556814400 is a `hidden beast` number, since 2 + 155 + 68 + 1 + 440 + 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 143 ways as a sum of consecutive naturals, for example, 222235152 + ... + 222235248.

It is an arithmetic number, because the mean of its divisors is an integer number (88850216).

Almost surely, 2^21556814400 is an apocalyptic number.

21556814400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21556814400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44780508864).

21556814400 is an abundant number, since it is smaller than the sum of its proper divisors (68004203328).

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

21556814400 is a wasteful number, since it uses less digits than its factorization.

21556814400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 202 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

It can be divided in two parts, 2155681 and 4400, that added together give a triangular number (2160081 = T₂₀₇₈).

The spelling of 21556814400 in words is "twenty-one billion, five hundred fifty-six million, eight hundred fourteen thousand, four hundred".