21366561024 has 360 divisors, whose sum is σ = 67382929152. Its totient is φ = 6723440640.

The previous prime is 21366561019. The next prime is 21366561049. The reversal of 21366561024 is 42016566312.

21366561024 is a `hidden beast` number, since 2 + 1 + 36 + 6 + 5 + 610 + 2 + 4 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21366561024.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 27640702 + ... + 27641474.

Almost surely, 2^21366561024 is an apocalyptic number.

21366561024 is a gapful number since it is divisible by the number (24) 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 21366561024, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33691464576).

21366561024 is an abundant number, since it is smaller than the sum of its proper divisors (46016368128).

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

21366561024 is an equidigital number, since it uses as much as digits as its factorization.

21366561024 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 875 (or 852 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 21366561024 in words is "twenty-one billion, three hundred sixty-six million, five hundred sixty-one thousand, twenty-four".