390640 has 40 divisors (see below), whose sum is σ = 959760. Its totient is φ = 147456.

The previous prime is 390581. The next prime is 390647. The reversal of 390640 is 46093.

It is a tau number, because it is divible by the number of its divisors (40).

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (390647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1392 + ... + 1648.

It is an arithmetic number, because the mean of its divisors is an integer number (23994).

2³⁹⁰⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 390640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (479880).

390640 is an abundant number, since it is smaller than the sum of its proper divisors (569120).

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

390640 is a wasteful number, since it uses less digits than its factorization.

390640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289 (or 283 counting only the distinct ones).

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

The square root of 390640 is about 625.0119998848. The cubic root of 390640 is about 73.1013791290.

The spelling of 390640 in words is "three hundred ninety thousand, six hundred forty".