31551121505 has 4 divisors (see below), whose sum is σ = 37861345812. Its totient is φ = 25240897200.

The previous prime is 31551121477. The next prime is 31551121513. The reversal of 31551121505 is 50512115513.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50512115513 = 2243 ⋅22519891.

It can be written as a sum of positive squares in 2 ways, for example, as 23550892369 + 8000229136 = 153463^2 + 89444^2 .

It is not a de Polignac number, because 31551121505 - 2²⁸ = 31282686049 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3155112146 + ... + 3155112155.

It is an arithmetic number, because the mean of its divisors is an integer number (9465336453).

Almost surely, 2^31551121505 is an apocalyptic number.

It is an amenable number.

31551121505 is a deficient number, since it is larger than the sum of its proper divisors (6310224307).

31551121505 is an equidigital number, since it uses as much as digits as its factorization.

31551121505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6310224306.

The product of its (nonzero) digits is 3750, while the sum is 29.

The spelling of 31551121505 in words is "thirty-one billion, five hundred fifty-one million, one hundred twenty-one thousand, five hundred five".