31105012561 has 4 divisors (see below), whose sum is σ = 35548585792. Its totient is φ = 26661439332.

The previous prime is 31105012553. The next prime is 31105012571. The reversal of 31105012561 is 16521050113.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 31105012561 - 2³ = 31105012553 is a prime.

It is a super-3 number, since 3×31105012561³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31105012501) 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, 2221786605 + ... + 2221786618.

It is an arithmetic number, because the mean of its divisors is an integer number (8887146448).

Almost surely, 2^31105012561 is an apocalyptic number.

It is an amenable number.

31105012561 is a deficient number, since it is larger than the sum of its proper divisors (4443573231).

31105012561 is an equidigital number, since it uses as much as digits as its factorization.

31105012561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4443573230.

The product of its (nonzero) digits is 900, while the sum is 25.

Adding to 31105012561 its reverse (16521050113), we get a palindrome (47626062674).

The spelling of 31105012561 in words is "thirty-one billion, one hundred five million, twelve thousand, five hundred sixty-one".