21405772800 has 924 divisors, whose sum is σ = 84339937216. Its totient is φ = 5374771200.

The previous prime is 21405772793. The next prime is 21405772807. The reversal of 21405772800 is 827750412.

21405772800 is a `hidden beast` number, since 2 + 1 + 4 + 0 + 577 + 2 + 80 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21405772793) and next prime (21405772807).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21405772807) by changing a digit.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 578534382 + ... + 578534418.

Almost surely, 2^21405772800 is an apocalyptic number.

21405772800 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 21405772800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42169968608).

21405772800 is an abundant number, since it is smaller than the sum of its proper divisors (62934164416).

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

21405772800 is an equidigital number, since it uses as much as digits as its factorization.

21405772800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 31360, while the sum is 36.

The spelling of 21405772800 in words is "twenty-one billion, four hundred five million, seven hundred seventy-two thousand, eight hundred".