309221947 has 2 divisors, whose sum is σ = 309221948. Its totient is φ = 309221946.

The previous prime is 309221923. The next prime is 309221953. The reversal of 309221947 is 749122903.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 309221947 - 2⁷ = 309221819 is a prime.

It is a Chen prime.

It is equal to p_16724719 and since 309221947 and 16724719 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (309221047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154610973 + 154610974.

It is an arithmetic number, because the mean of its divisors is an integer number (154610974).

Almost surely, 2^309221947 is an apocalyptic number.

309221947 is a deficient number, since it is larger than the sum of its proper divisors (1).

309221947 is an equidigital number, since it uses as much as digits as its factorization.

309221947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 309221947 is about 17584.7077598691. The cubic root of 309221947 is about 676.2232574617.

The spelling of 309221947 in words is "three hundred nine million, two hundred twenty-one thousand, nine hundred forty-seven".