309921961 has 2 divisors, whose sum is σ = 309921962. Its totient is φ = 309921960.

The previous prime is 309921923. The next prime is 309921979. The reversal of 309921961 is 169129903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 191656336 + 118265625 = 13844^2 + 10875^2 .

It is a cyclic number.

It is not a de Polignac number, because 309921961 - 2²¹ = 307824809 is a prime.

It is not a weakly prime, because it can be changed into another prime (309921061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154960980 + 154960981.

It is an arithmetic number, because the mean of its divisors is an integer number (154960981).

Almost surely, 2^309921961 is an apocalyptic number.

It is an amenable number.

309921961 is a deficient number, since it is larger than the sum of its proper divisors (1).

309921961 is an equidigital number, since it uses as much as digits as its factorization.

309921961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26244, while the sum is 40.

The square root of 309921961 is about 17604.6005634891. The cubic root of 309921961 is about 676.7331490353.

The spelling of 309921961 in words is "three hundred nine million, nine hundred twenty-one thousand, nine hundred sixty-one".