31561764021 has 16 divisors (see below), whose sum is σ = 46760925120. Its totient is φ = 21039935760.

The previous prime is 31561763957. The next prime is 31561764023. The reversal of 31561764021 is 12046716513.

31561764021 is a `hidden beast` number, since 3 + 1 + 5 + 6 + 1 + 7 + 640 + 2 + 1 = 666.

It is not a de Polignac number, because 31561764021 - 2⁶ = 31561763957 is a prime.

It is a super-2 number, since 2×31561764021² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31561764023) 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 15 ways as a sum of consecutive naturals, for example, 796351 + ... + 835043.

It is an arithmetic number, because the mean of its divisors is an integer number (2922557820).

Almost surely, 2^31561764021 is an apocalyptic number.

It is an amenable number.

31561764021 is a deficient number, since it is larger than the sum of its proper divisors (15199161099).

31561764021 is a wasteful number, since it uses less digits than its factorization.

31561764021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68913 (or 68907 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 31561764021 in words is "thirty-one billion, five hundred sixty-one million, seven hundred sixty-four thousand, twenty-one".