309664 has 12 divisors (see below), whose sum is σ = 609714. Its totient is φ = 154816.

The previous prime is 309637. The next prime is 309667. The reversal of 309664 is 466903.

It can be written as a sum of positive squares in only one way, i.e., 242064 + 67600 = 492^2 + 260^2 .

It is not an unprimeable number, because it can be changed into a prime (309667) by changing a digit.

309664 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4807 + ... + 4870.

2³⁰⁹⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

309664 is a deficient number, since it is larger than the sum of its proper divisors (300050).

309664 is an equidigital number, since it uses as much as digits as its factorization.

309664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9687 (or 9679 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 309664 is about 556.4746175703. The cubic root of 309664 is about 67.6545339158.

It can be divided in two parts, 3096 and 64, that added together give a triangular number (3160 = T₇₉).

The spelling of 309664 in words is "three hundred nine thousand, six hundred sixty-four".