21715328880 has 400 divisors, whose sum is σ = 88981161984. Its totient is φ = 4803079680.

The previous prime is 21715328861. The next prime is 21715328881. The reversal of 21715328880 is 8882351712.

21715328880 is a `hidden beast` number, since 217 + 153 + 288 + 8 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21715328881) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1398439 + ... + 1413881.

Almost surely, 2^21715328880 is an apocalyptic number.

21715328880 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 21715328880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44490580992).

21715328880 is an abundant number, since it is smaller than the sum of its proper divisors (67265833104).

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

21715328880 is a wasteful number, since it uses less digits than its factorization.

21715328880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15506 (or 15491 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 21715328880 in words is "twenty-one billion, seven hundred fifteen million, three hundred twenty-eight thousand, eight hundred eighty".