31221131213 has 4 divisors (see below), whose sum is σ = 31285240800. Its totient is φ = 31157021628.

The previous prime is 31221131177. The next prime is 31221131219. The reversal of 31221131213 is 31213112213.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31213112213 = 1949 ⋅16014937.

It is a cyclic number.

It is not a de Polignac number, because 31221131213 - 2¹⁴ = 31221114829 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 (31221131219) 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, 32054063 + ... + 32055036.

It is an arithmetic number, because the mean of its divisors is an integer number (7821310200).

Almost surely, 2^31221131213 is an apocalyptic number.

It is an amenable number.

31221131213 is a deficient number, since it is larger than the sum of its proper divisors (64109587).

31221131213 is an equidigital number, since it uses as much as digits as its factorization.

31221131213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64109586.

The product of its digits is 216, while the sum is 20.

Adding to 31221131213 its reverse (31213112213), we get a palindrome (62434243426).

The spelling of 31221131213 in words is "thirty-one billion, two hundred twenty-one million, one hundred thirty-one thousand, two hundred thirteen".