31821087861 has 12 divisors (see below), whose sum is σ = 45978947820. Its totient is φ = 21207064320.

The previous prime is 31821087791. The next prime is 31821087863. The reversal of 31821087861 is 16878012813.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18470440836 + 13350647025 = 135906^2 + 115545^2 .

It is not a de Polignac number, because 31821087861 - 2⁷ = 31821087733 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31821087863) 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 11 ways as a sum of consecutive naturals, for example, 553966 + ... + 608703.

It is an arithmetic number, because the mean of its divisors is an integer number (3831578985).

Almost surely, 2^31821087861 is an apocalyptic number.

It is an amenable number.

31821087861 is a deficient number, since it is larger than the sum of its proper divisors (14157859959).

31821087861 is a wasteful number, since it uses less digits than its factorization.

31821087861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1165716 (or 1165713 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The spelling of 31821087861 in words is "thirty-one billion, eight hundred twenty-one million, eighty-seven thousand, eight hundred sixty-one".