309440 has 28 divisors (see below), whose sum is σ = 737616. Its totient is φ = 123648.

The previous prime is 309437. The next prime is 309457. The reversal of 309440 is 44903.

309440 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×309440² = 191506227200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 309440.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164 + ... + 803.

2³⁰⁹⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

309440 is an abundant number, since it is smaller than the sum of its proper divisors (428176).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

309440 is an equidigital number, since it uses as much as digits as its factorization.

309440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 984 (or 974 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 309440 is about 556.2733141182. The cubic root of 309440 is about 67.6382170141.

The spelling of 309440 in words is "three hundred nine thousand, four hundred forty".