31821108857 has 4 divisors (see below), whose sum is σ = 33495904080. Its totient is φ = 30146313636.

The previous prime is 31821108817. The next prime is 31821108859. The reversal of 31821108857 is 75880112813.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75880112813 = 59 ⋅1286103607.

It is a cyclic number.

It is not a de Polignac number, because 31821108857 - 2²⁰ = 31820060281 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31821108859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 837397583 + ... + 837397620.

It is an arithmetic number, because the mean of its divisors is an integer number (8373976020).

Almost surely, 2^31821108857 is an apocalyptic number.

It is an amenable number.

31821108857 is a deficient number, since it is larger than the sum of its proper divisors (1674795223).

31821108857 is a wasteful number, since it uses less digits than its factorization.

31821108857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1674795222.

The product of its (nonzero) digits is 107520, while the sum is 44.

The spelling of 31821108857 in words is "thirty-one billion, eight hundred twenty-one million, one hundred eight thousand, eight hundred fifty-seven".