331664521 has 2 divisors, whose sum is σ = 331664522. Its totient is φ = 331664520.

The previous prime is 331664467. The next prime is 331664527. The reversal of 331664521 is 125466133.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 318444025 + 13220496 = 17845^2 + 3636^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-331664521 is a prime.

It is a super-2 number, since 2×331664521² = 220002708980318882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (331664527) 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, 165832260 + 165832261.

It is an arithmetic number, because the mean of its divisors is an integer number (165832261).

Almost surely, 2^331664521 is an apocalyptic number.

It is an amenable number.

331664521 is a deficient number, since it is larger than the sum of its proper divisors (1).

331664521 is an equidigital number, since it uses as much as digits as its factorization.

331664521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 31.

The square root of 331664521 is about 18211.6589304764. The cubic root of 331664521 is about 692.2022481500.

The spelling of 331664521 in words is "three hundred thirty-one million, six hundred sixty-four thousand, five hundred twenty-one".