21536723880 has 320 divisors, whose sum is σ = 83969043840. Its totient is φ = 4848864768.

The previous prime is 21536723863. The next prime is 21536723933. The reversal of 21536723880 is 8832763512.

21536723880 is a `hidden beast` number, since 2 + 1 + 536 + 7 + 2 + 38 + 80 = 666.

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 79 ways as a sum of consecutive naturals, for example, 1512474 + ... + 1526646.

It is an arithmetic number, because the mean of its divisors is an integer number (262403262).

Almost surely, 2^21536723880 is an apocalyptic number.

21536723880 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 21536723880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41984521920).

21536723880 is an abundant number, since it is smaller than the sum of its proper divisors (62432319960).

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

21536723880 is a wasteful number, since it uses less digits than its factorization.

21536723880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14270 (or 14257 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 21536723880 in words is "twenty-one billion, five hundred thirty-six million, seven hundred twenty-three thousand, eight hundred eighty".