31313222221 has 4 divisors (see below), whose sum is σ = 31313945692. Its totient is φ = 31312498752.

The previous prime is 31313222209. The next prime is 31313222243. The reversal of 31313222221 is 12222231313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12222231313 = 71 ⋅172144103.

It can be written as a sum of positive squares in 2 ways, for example, as 23768388900 + 7544833321 = 154170^2 + 86861^2 .

It is a cyclic number.

It is not a de Polignac number, because 31313222221 - 2²⁵ = 31279667789 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31313222192 and 31313222201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31313262221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 292380 + ... + 384853.

It is an arithmetic number, because the mean of its divisors is an integer number (7828486423).

Almost surely, 2^31313222221 is an apocalyptic number.

It is an amenable number.

31313222221 is a deficient number, since it is larger than the sum of its proper divisors (723471).

31313222221 is an equidigital number, since it uses as much as digits as its factorization.

31313222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 723470.

The product of its digits is 864, while the sum is 22.

Adding to 31313222221 its reverse (12222231313), we get a palindrome (43535453534).

The spelling of 31313222221 in words is "thirty-one billion, three hundred thirteen million, two hundred twenty-two thousand, two hundred twenty-one".