390691 has 4 divisors (see below), whose sum is σ = 446512. Its totient is φ = 334872.

The previous prime is 390673. The next prime is 390703. The reversal of 390691 is 196093.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196093 = 157 ⋅1249.

It is a cyclic number.

It is not a de Polignac number, because 390691 - 2¹⁷ = 259619 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (390671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27900 + ... + 27913.

It is an arithmetic number, because the mean of its divisors is an integer number (111628).

2³⁹⁰⁶⁹¹ is an apocalyptic number.

390691 is a deficient number, since it is larger than the sum of its proper divisors (55821).

390691 is an equidigital number, since it uses as much as digits as its factorization.

390691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55820.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 390691 is about 625.0527977699. The cubic root of 390691 is about 73.1045602404.

It can be divided in two parts, 390 and 691, that added together give a triangular number (1081 = T₄₆).

The spelling of 390691 in words is "three hundred ninety thousand, six hundred ninety-one".