21639405732 has 24 divisors (see below), whose sum is σ = 57705082176. Its totient is φ = 6182687328.

The previous prime is 21639405727. The next prime is 21639405737. The reversal of 21639405732 is 23750493612.

It is an interprime number because it is at equal distance from previous prime (21639405727) and next prime (21639405737).

It is a super-2 number, since 2×21639405732² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (21639405737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128805903 + ... + 128806070.

It is an arithmetic number, because the mean of its divisors is an integer number (2404378424).

Almost surely, 2^21639405732 is an apocalyptic number.

It is an amenable number.

21639405732 is an abundant number, since it is smaller than the sum of its proper divisors (36065676444).

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

21639405732 is a wasteful number, since it uses less digits than its factorization.

21639405732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257611987 (or 257611985 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 42.

The spelling of 21639405732 in words is "twenty-one billion, six hundred thirty-nine million, four hundred five thousand, seven hundred thirty-two".