31212130220021 has 32 divisors (see below), whose sum is σ = 32501215111680. Its totient is φ = 29951572953600.

The previous prime is 31212130219979. The next prime is 31212130220039. The reversal of 31212130220021 is 12002203121213.

It is a de Polignac number, because none of the positive numbers 2^k-31212130220021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31212130219975 and 31212130220002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31212130220041) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1376852675 + ... + 1376875343.

It is an arithmetic number, because the mean of its divisors is an integer number (1015662972240).

Almost surely, 2^{31212130220021} is an apocalyptic number.

It is an amenable number.

31212130220021 is a deficient number, since it is larger than the sum of its proper divisors (1289084891659).

31212130220021 is a wasteful number, since it uses less digits than its factorization.

31212130220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24557.

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 31212130220021 its reverse (12002203121213), we get a palindrome (43214333341234).

The spelling of 31212130220021 in words is "thirty-one trillion, two hundred twelve billion, one hundred thirty million, two hundred twenty thousand, twenty-one".