309720091 has 2 divisors, whose sum is σ = 309720092. Its totient is φ = 309720090.

The previous prime is 309720067. The next prime is 309720097. The reversal of 309720091 is 190027903.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 309720091 - 2¹⁷ = 309589019 is a prime.

It is not a weakly prime, because it can be changed into another prime (309720097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154860045 + 154860046.

It is an arithmetic number, because the mean of its divisors is an integer number (154860046).

Almost surely, 2^309720091 is an apocalyptic number.

309720091 is a deficient number, since it is larger than the sum of its proper divisors (1).

309720091 is an equidigital number, since it uses as much as digits as its factorization.

309720091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402, while the sum is 31.

The square root of 309720091 is about 17598.8661850700. The cubic root of 309720091 is about 676.5861853801.

Adding to 309720091 its reverse (190027903), we get a palindrome (499747994).

The spelling of 309720091 in words is "three hundred nine million, seven hundred twenty thousand, ninety-one".