21856158720 has 528 divisors, whose sum is σ = 85729146048. Its totient is φ = 5295144960.

The previous prime is 21856158719. The next prime is 21856158739. The reversal of 21856158720 is 2785165812.

21856158720 is a `hidden beast` number, since 2 + 1 + 8 + 5 + 61 + 587 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (528).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13684962 + ... + 13686558.

Almost surely, 2^21856158720 is an apocalyptic number.

21856158720 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 21856158720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42864573024).

21856158720 is an abundant number, since it is smaller than the sum of its proper divisors (63872987328).

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

21856158720 is a wasteful number, since it uses less digits than its factorization.

21856158720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1648 (or 1618 counting only the distinct ones).

The product of its (nonzero) digits is 268800, while the sum is 45.

The spelling of 21856158720 in words is "twenty-one billion, eight hundred fifty-six million, one hundred fifty-eight thousand, seven hundred twenty".