21639340800 has 1944 divisors, whose sum is σ = 106488778032. Its totient is φ = 4128768000.

The previous prime is 21639340757. The next prime is 21639340831. The reversal of 21639340800 is 804393612.

21639340800 is a `hidden beast` number, since 2 + 163 + 93 + 408 + 0 + 0 = 666.

It is a super-2 number, since 2×21639340800² (a number of 21 digits) contains 22 as substring.

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 215 ways as a sum of consecutive naturals, for example, 527788780 + ... + 527788820.

It is an arithmetic number, because the mean of its divisors is an integer number (54778178).

Almost surely, 2^21639340800 is an apocalyptic number.

21639340800 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 21639340800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53244389016).

21639340800 is an abundant number, since it is smaller than the sum of its proper divisors (84849437232).

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

21639340800 is a wasteful number, since it uses less digits than its factorization.

21639340800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The spelling of 21639340800 in words is "twenty-one billion, six hundred thirty-nine million, three hundred forty thousand, eight hundred".