31221131231 has 2 divisors, whose sum is σ = 31221131232. Its totient is φ = 31221131230.

The previous prime is 31221131219. The next prime is 31221131239. The reversal of 31221131231 is 13213112213.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31221131231 - 2³⁰ = 30147389407 is a prime.

It is a super-2 number, since 2×31221131231² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31221131239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15610565615 + 15610565616.

It is an arithmetic number, because the mean of its divisors is an integer number (15610565616).

Almost surely, 2^31221131231 is an apocalyptic number.

31221131231 is a deficient number, since it is larger than the sum of its proper divisors (1).

31221131231 is an equidigital number, since it uses as much as digits as its factorization.

31221131231 is an evil number, because the sum of its binary digits is even.

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

Adding to 31221131231 its reverse (13213112213), we get a palindrome (44434243444).

The spelling of 31221131231 in words is "thirty-one billion, two hundred twenty-one million, one hundred thirty-one thousand, two hundred thirty-one".