21543317631 has 16 divisors (see below), whose sum is σ = 34817483520. Its totient is φ = 13056555960.

The previous prime is 21543317629. The next prime is 21543317633. The reversal of 21543317631 is 13671334512.

21543317631 is a `hidden beast` number, since 2 + 1 + 5 + 4 + 3 + 3 + 17 + 631 = 666.

It is an interprime number because it is at equal distance from previous prime (21543317629) and next prime (21543317633).

It is not a de Polignac number, because 21543317631 - 2¹ = 21543317629 is a prime.

It is a super-2 number, since 2×21543317631² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543317633) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36267915 + ... + 36268508.

It is an arithmetic number, because the mean of its divisors is an integer number (2176092720).

Almost surely, 2^21543317631 is an apocalyptic number.

21543317631 is a deficient number, since it is larger than the sum of its proper divisors (13274165889).

21543317631 is a wasteful number, since it uses less digits than its factorization.

21543317631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72536443 (or 72536437 counting only the distinct ones).

The product of its digits is 45360, while the sum is 36.

The spelling of 21543317631 in words is "twenty-one billion, five hundred forty-three million, three hundred seventeen thousand, six hundred thirty-one".