390991865 has 32 divisors (see below), whose sum is σ = 526559616. Its totient is φ = 276290560.

The previous prime is 390991813. The next prime is 390991873. The reversal of 390991865 is 568199093.

It is not a de Polignac number, because 390991865 - 2⁶ = 390991801 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 328802 + ... + 329988.

It is an arithmetic number, because the mean of its divisors is an integer number (16454988).

Almost surely, 2^390991865 is an apocalyptic number.

It is an amenable number.

390991865 is a deficient number, since it is larger than the sum of its proper divisors (135567751).

390991865 is a wasteful number, since it uses less digits than its factorization.

390991865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1369.

The product of its (nonzero) digits is 524880, while the sum is 50.

The square root of 390991865 is about 19773.5142298985. The cubic root of 390991865 is about 731.2332098319.

The spelling of 390991865 in words is "three hundred ninety million, nine hundred ninety-one thousand, eight hundred sixty-five".