309939481 has 2 divisors, whose sum is σ = 309939482. Its totient is φ = 309939480.

The previous prime is 309939431. The next prime is 309939523. The reversal of 309939481 is 184939903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 288456256 + 21483225 = 16984^2 + 4635^2 .

It is an emirp because it is prime and its reverse (184939903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 309939481 - 2¹³ = 309931289 is a prime.

It is a super-2 number, since 2×309939481² = 192124963765098722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (309939431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154969740 + 154969741.

It is an arithmetic number, because the mean of its divisors is an integer number (154969741).

Almost surely, 2^309939481 is an apocalyptic number.

It is an amenable number.

309939481 is a deficient number, since it is larger than the sum of its proper divisors (1).

309939481 is an equidigital number, since it uses as much as digits as its factorization.

309939481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 46.

The square root of 309939481 is about 17605.0981536599. The cubic root of 309939481 is about 676.7459007845.

The spelling of 309939481 in words is "three hundred nine million, nine hundred thirty-nine thousand, four hundred eighty-one".