21639052731 has 8 divisors (see below), whose sum is σ = 29631856144. Its totient is φ = 14036142240.

The previous prime is 21639052727. The next prime is 21639052741. The reversal of 21639052731 is 13725093612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21639052731 - 2² = 21639052727 is a prime.

It is a super-2 number, since 2×21639052731² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21639052731.

It is not an unprimeable number, because it can be changed into a prime (21639052741) 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, 97473100 + ... + 97473321.

It is an arithmetic number, because the mean of its divisors is an integer number (3703982018).

Almost surely, 2^21639052731 is an apocalyptic number.

21639052731 is a deficient number, since it is larger than the sum of its proper divisors (7992803413).

21639052731 is a wasteful number, since it uses less digits than its factorization.

21639052731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194946461.

The product of its (nonzero) digits is 68040, while the sum is 39.

The spelling of 21639052731 in words is "twenty-one billion, six hundred thirty-nine million, fifty-two thousand, seven hundred thirty-one".