390661 has 4 divisors (see below), whose sum is σ = 392524. Its totient is φ = 388800.

The previous prime is 390653. The next prime is 390671. The reversal of 390661 is 166093.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 297025 + 93636 = 545^2 + 306^2 .

It is a 5-Lehmer number, since φ(390661) divides (390661-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 390661 - 2³ = 390653 is a prime.

It is a Duffinian number.

It is a congruent number.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 570 + ... + 1051.

It is an arithmetic number, because the mean of its divisors is an integer number (98131).

2³⁹⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

390661 is a deficient number, since it is larger than the sum of its proper divisors (1863).

390661 is a wasteful number, since it uses less digits than its factorization.

390661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1862.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 390661 is about 625.0287993365. The cubic root of 390661 is about 73.1026890320.

The spelling of 390661 in words is "three hundred ninety thousand, six hundred sixty-one".