331618921 has 2 divisors, whose sum is σ = 331618922. Its totient is φ = 331618920.

The previous prime is 331618909. The next prime is 331618927. The reversal of 331618921 is 129816133.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 247621696 + 83997225 = 15736^2 + 9165^2 .

It is a cyclic number.

It is not a de Polignac number, because 331618921 - 2¹³ = 331610729 is a prime.

It is a super-2 number, since 2×331618921² = 219942217530408482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (331618927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165809460 + 165809461.

It is an arithmetic number, because the mean of its divisors is an integer number (165809461).

Almost surely, 2^331618921 is an apocalyptic number.

It is an amenable number.

331618921 is a deficient number, since it is larger than the sum of its proper divisors (1).

331618921 is an equidigital number, since it uses as much as digits as its factorization.

331618921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 331618921 is about 18210.4069421856. The cubic root of 331618921 is about 692.1705234531.

The spelling of 331618921 in words is "three hundred thirty-one million, six hundred eighteen thousand, nine hundred twenty-one".