390615685 has 4 divisors (see below), whose sum is σ = 468738828. Its totient is φ = 312492544.

The previous prime is 390615653. The next prime is 390615691. The reversal of 390615685 is 586516093.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 586516093 = 103 ⋅5694331.

It can be written as a sum of positive squares in 2 ways, for example, as 172108161 + 218507524 = 13119^2 + 14782^2 .

It is a cyclic number.

It is not a de Polignac number, because 390615685 - 2⁵ = 390615653 is a prime.

It is a super-2 number, since 2×390615685² = 305161226736038450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

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, 39061564 + ... + 39061573.

It is an arithmetic number, because the mean of its divisors is an integer number (117184707).

Almost surely, 2^390615685 is an apocalyptic number.

It is an amenable number.

390615685 is a deficient number, since it is larger than the sum of its proper divisors (78123143).

390615685 is an equidigital number, since it uses as much as digits as its factorization.

390615685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78123142.

The product of its (nonzero) digits is 194400, while the sum is 43.

The square root of 390615685 is about 19763.9997217162. Note that the first 3 decimals coincide. The cubic root of 390615685 is about 730.9986238990.

It can be divided in two parts, 3906 and 15685, that added together give a palindrome (19591).

The spelling of 390615685 in words is "three hundred ninety million, six hundred fifteen thousand, six hundred eighty-five".