31561533540 has 72 divisors (see below), whose sum is σ = 98324149560. Its totient is φ = 8188936704.

The previous prime is 31561533539. The next prime is 31561533559. The reversal of 31561533540 is 4533516513.

31561533540 is a `hidden beast` number, since 3 + 1 + 5 + 61 + 53 + 3 + 540 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 2916648036 + 28644885504 = 54006^2 + 169248^2 .

It is a super-2 number, since 2×31561533540² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 31561533495 and 31561533504.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2362825 + ... + 2376144.

Almost surely, 2^31561533540 is an apocalyptic number.

31561533540 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31561533540 is an abundant number, since it is smaller than the sum of its proper divisors (66762616020).

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

31561533540 is a wasteful number, since it uses less digits than its factorization.

31561533540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4739021 (or 4739016 counting only the distinct ones).

The product of its (nonzero) digits is 81000, while the sum is 36.

The spelling of 31561533540 in words is "thirty-one billion, five hundred sixty-one million, five hundred thirty-three thousand, five hundred forty".