21366936864 has 360 divisors, whose sum is σ = 78728179068. Its totient is φ = 5634800640.

The previous prime is 21366936839. The next prime is 21366936953. The reversal of 21366936864 is 46863966312.

21366936864 is a `hidden beast` number, since 213 + 6 + 6 + 9 + 368 + 64 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21289144464 + 77792400 = 145908^2 + 8820^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21366936864.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 1644634 + ... + 1657574.

Almost surely, 2^21366936864 is an apocalyptic number.

21366936864 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 21366936864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39364089534).

21366936864 is an abundant number, since it is smaller than the sum of its proper divisors (57361242204).

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

21366936864 is a wasteful number, since it uses less digits than its factorization.

21366936864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12990 (or 12966 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 54.

The spelling of 21366936864 in words is "twenty-one billion, three hundred sixty-six million, nine hundred thirty-six thousand, eight hundred sixty-four".