21536620704 has 72 divisors (see below), whose sum is σ = 61275794580. Its totient is φ = 7175236608.

The previous prime is 21536620691. The next prime is 21536620709. The reversal of 21536620704 is 40702663512.

21536620704 is a `hidden beast` number, since 21 + 5 + 3 + 6 + 620 + 7 + 0 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21506809104 + 29811600 = 146652^2 + 5460^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×21536620704² (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 not an unprimeable number, because it can be changed into a prime (21536620709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 583734 + ... + 619530.

Almost surely, 2^21536620704 is an apocalyptic number.

21536620704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21536620704 is an abundant number, since it is smaller than the sum of its proper divisors (39739173876).

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

21536620704 is a wasteful number, since it uses less digits than its factorization.

21536620704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37902 (or 37891 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21536620704 in words is "twenty-one billion, five hundred thirty-six million, six hundred twenty thousand, seven hundred four".