21315663531 has 24 divisors (see below), whose sum is σ = 30865770000. Its totient is φ = 14175196992.

The previous prime is 21315663529. The next prime is 21315663541. The reversal of 21315663531 is 13536651312.

21315663531 is a `hidden beast` number, since 2 + 1 + 3 + 15 + 6 + 635 + 3 + 1 = 666.

It is not a de Polignac number, because 21315663531 - 2¹ = 21315663529 is a prime.

It is a super-2 number, since 2×21315663531² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21315663511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10301365 + ... + 10303433.

It is an arithmetic number, because the mean of its divisors is an integer number (1286073750).

Almost surely, 2^21315663531 is an apocalyptic number.

21315663531 is a deficient number, since it is larger than the sum of its proper divisors (9550106469).

21315663531 is a wasteful number, since it uses less digits than its factorization.

21315663531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4363 (or 4360 counting only the distinct ones).

The product of its digits is 48600, while the sum is 36.

The spelling of 21315663531 in words is "twenty-one billion, three hundred fifteen million, six hundred sixty-three thousand, five hundred thirty-one".