31213331221 has 4 divisors (see below), whose sum is σ = 31217126112. Its totient is φ = 31209536332.

The previous prime is 31213331209. The next prime is 31213331231. The reversal of 31213331221 is 12213331213.

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: 12213331213 = 11047 ⋅1105579.

It is a cyclic number.

It is not a de Polignac number, because 31213331221 - 2¹⁵ = 31213298453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31213331192 and 31213331201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31213331231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1885081 + ... + 1901566.

It is an arithmetic number, because the mean of its divisors is an integer number (7804281528).

Almost surely, 2^31213331221 is an apocalyptic number.

It is an amenable number.

31213331221 is a deficient number, since it is larger than the sum of its proper divisors (3794891).

31213331221 is an equidigital number, since it uses as much as digits as its factorization.

31213331221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3794890.

The product of its digits is 648, while the sum is 22.

Adding to 31213331221 its reverse (12213331213), we get a palindrome (43426662434).

The spelling of 31213331221 in words is "thirty-one billion, two hundred thirteen million, three hundred thirty-one thousand, two hundred twenty-one".