309640 has 16 divisors (see below), whose sum is σ = 696780. Its totient is φ = 123840.

The previous prime is 309637. The next prime is 309667. The reversal of 309640 is 46903.

309640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 293764 + 15876 = 542^2 + 126^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3831 + ... + 3910.

2³⁰⁹⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

309640 is an abundant number, since it is smaller than the sum of its proper divisors (387140).

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

309640 is a wasteful number, since it uses less digits than its factorization.

309640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7752 (or 7748 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 309640 is about 556.4530528266. The cubic root of 309640 is about 67.6527860528.

It can be divided in two parts, 3096 and 40, that added together give a square (3136 = 56²).

The spelling of 309640 in words is "three hundred nine thousand, six hundred forty".