390663661 has 6 divisors (see below), whose sum is σ = 396093930. Its totient is φ = 385306848.

The previous prime is 390663641. The next prime is 390663677. The reversal of 390663661 is 166366093.

It can be written as a sum of positive squares in 3 ways, for example, as 22752900 + 367910761 = 4770^2 + 19181^2 .

It is not a de Polignac number, because 390663661 - 2⁹ = 390663149 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 (390663641) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 31326 + ... + 41983.

It is an arithmetic number, because the mean of its divisors is an integer number (66015655).

Almost surely, 2^390663661 is an apocalyptic number.

It is an amenable number.

390663661 is a deficient number, since it is larger than the sum of its proper divisors (5430269).

390663661 is an frugal number, since it uses more digits than its factorization.

390663661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73455 (or 73382 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 40.

The square root of 390663661 is about 19765.2134063865. The cubic root of 390663661 is about 731.0285501203.

The spelling of 390663661 in words is "three hundred ninety million, six hundred sixty-three thousand, six hundred sixty-one".