31561121313 has 10 divisors (see below), whose sum is σ = 47146860354. Its totient is φ = 21040747488.

The previous prime is 31561121279. The next prime is 31561121329. The reversal of 31561121313 is 31312116513.

It is a happy number.

31561121313 is a `hidden beast` number, since 3 + 15 + 611 + 2 + 1 + 31 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 22030871184 + 9530250129 = 148428^2 + 97623^2 .

It is not a de Polignac number, because 31561121313 - 2⁸ = 31561121057 is a prime.

It is a super-2 number, since 2×31561121313² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (31561121363) by changing a digit.

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 9 ways as a sum of consecutive naturals, for example, 194821656 + ... + 194821817.

Almost surely, 2^31561121313 is an apocalyptic number.

It is an amenable number.

31561121313 is a deficient number, since it is larger than the sum of its proper divisors (15585739041).

31561121313 is an equidigital number, since it uses as much as digits as its factorization.

31561121313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389643485 (or 389643476 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

Adding to 31561121313 its reverse (31312116513), we get a palindrome (62873237826).

It can be divided in two parts, 31 and 561121313, that added together give a square (561121344 = 23688²).

The spelling of 31561121313 in words is "thirty-one billion, five hundred sixty-one million, one hundred twenty-one thousand, three hundred thirteen".