309139 has 4 divisors (see below), whose sum is σ = 312424. Its totient is φ = 305856.

The previous prime is 309137. The next prime is 309157. The reversal of 309139 is 931903.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 309139 - 2¹ = 309137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (309131) 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 3 ways as a sum of consecutive naturals, for example, 1497 + ... + 1690.

It is an arithmetic number, because the mean of its divisors is an integer number (78106).

2³⁰⁹¹³⁹ is an apocalyptic number.

309139 is a deficient number, since it is larger than the sum of its proper divisors (3285).

309139 is an equidigital number, since it uses as much as digits as its factorization.

309139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3284.

The product of its (nonzero) digits is 729, while the sum is 25.

The square root of 309139 is about 556.0026978352. The cubic root of 309139 is about 67.6162787728.

It can be divided in two parts, 30 and 9139, that multiplied together give a triangular number (274170 = T₇₄₀).

The spelling of 309139 in words is "three hundred nine thousand, one hundred thirty-nine".