31311001021 has 4 divisors (see below), whose sum is σ = 32321033344. Its totient is φ = 30300968700.

The previous prime is 31311000997. The next prime is 31311001031. The reversal of 31311001021 is 12010011313.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12010011313 = 163 ⋅73681051.

It is a cyclic number.

It is not a de Polignac number, because 31311001021 - 2⁵ = 31311000989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31311000992 and 31311001010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31311001031) 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, 505016115 + ... + 505016176.

It is an arithmetic number, because the mean of its divisors is an integer number (8080258336).

Almost surely, 2^31311001021 is an apocalyptic number.

31311001021 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31311001021 is a deficient number, since it is larger than the sum of its proper divisors (1010032323).

31311001021 is a wasteful number, since it uses less digits than its factorization.

31311001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010032322.

The product of its (nonzero) digits is 18, while the sum is 13.

Adding to 31311001021 its reverse (12010011313), we get a palindrome (43321012334).

The spelling of 31311001021 in words is "thirty-one billion, three hundred eleven million, one thousand, twenty-one".