31121134813 has 4 divisors (see below), whose sum is σ = 32951789820. Its totient is φ = 29290479808.

The previous prime is 31121134801. The next prime is 31121134831. The reversal of 31121134813 is 31843112113.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19055869849 + 12065264964 = 138043^2 + 109842^2 .

It is a cyclic number.

It is not a de Polignac number, because 31121134813 - 2⁹ = 31121134301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121134843) 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, 915327478 + ... + 915327511.

It is an arithmetic number, because the mean of its divisors is an integer number (8237947455).

Almost surely, 2^31121134813 is an apocalyptic number.

It is an amenable number.

31121134813 is a deficient number, since it is larger than the sum of its proper divisors (1830655007).

31121134813 is a wasteful number, since it uses less digits than its factorization.

31121134813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1830655006.

The product of its digits is 1728, while the sum is 28.

Adding to 31121134813 its reverse (31843112113), we get a palindrome (62964246926).

The spelling of 31121134813 in words is "thirty-one billion, one hundred twenty-one million, one hundred thirty-four thousand, eight hundred thirteen".