31310123021 has 4 divisors (see below), whose sum is σ = 31313045532. Its totient is φ = 31307200512.

The previous prime is 31310123003. The next prime is 31310123027. The reversal of 31310123021 is 12032101313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12032101313 = 4003 ⋅3005771.

It can be written as a sum of positive squares in 2 ways, for example, as 23781957796 + 7528165225 = 154214^2 + 86765^2 .

It is a cyclic number.

It is not a de Polignac number, because 31310123021 - 2²⁶ = 31243014157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31310123027) 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, 1445126 + ... + 1466631.

It is an arithmetic number, because the mean of its divisors is an integer number (7828261383).

Almost surely, 2^31310123021 is an apocalyptic number.

It is an amenable number.

31310123021 is a deficient number, since it is larger than the sum of its proper divisors (2922511).

31310123021 is a wasteful number, since it uses less digits than its factorization.

31310123021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2922510.

The product of its (nonzero) digits is 108, while the sum is 17.

Adding to 31310123021 its reverse (12032101313), we get a palindrome (43342224334).

The spelling of 31310123021 in words is "thirty-one billion, three hundred ten million, one hundred twenty-three thousand, twenty-one".