21639005316 has 18 divisors (see below), whose sum is σ = 54698596862. Its totient is φ = 7213001760.

The previous prime is 21639005309. The next prime is 21639005327. The reversal of 21639005316 is 61350093612.

21639005316 is a `hidden beast` number, since 2 + 1 + 639 + 0 + 0 + 5 + 3 + 16 = 666.

It can be written as a sum of positive squares in only one way, i.e., 13145539716 + 8493465600 = 114654^2 + 92160^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 601083481 = 21639005316 / (2 + 1 + 6 + 3 + 9 + 0 + 0 + 5 + 3 + 1 + 6).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 300541705 + ... + 300541776.

Almost surely, 2^21639005316 is an apocalyptic number.

It is an amenable number.

21639005316 is an abundant number, since it is smaller than the sum of its proper divisors (33059591546).

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

21639005316 is a wasteful number, since it uses less digits than its factorization.

21639005316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 601083491 (or 601083486 counting only the distinct ones).

The product of its (nonzero) digits is 29160, while the sum is 36.

Adding to 21639005316 its reverse (61350093612), we get a palindrome (82989098928).

The spelling of 21639005316 in words is "twenty-one billion, six hundred thirty-nine million, five thousand, three hundred sixteen".