309491 has 16 divisors (see below), whose sum is σ = 403200. Its totient is φ = 230688.

The previous prime is 309481. The next prime is 309493. The reversal of 309491 is 194903.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 309491 - 2¹⁰ = 308467 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 309491.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 309491.

It is not an unprimeable number, because it can be changed into a prime (309493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1640 + ... + 1818.

It is an arithmetic number, because the mean of its divisors is an integer number (25200).

2³⁰⁹⁴⁹¹ is an apocalyptic number.

309491 is a deficient number, since it is larger than the sum of its proper divisors (93709).

309491 is a wasteful number, since it uses less digits than its factorization.

309491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 309491 is about 556.3191530048. The cubic root of 309491 is about 67.6419327151.

The spelling of 309491 in words is "three hundred nine thousand, four hundred ninety-one".