399065661 has 6 divisors (see below), whose sum is σ = 576428190. Its totient is φ = 266043768.

The previous prime is 399065647. The next prime is 399065687. The reversal of 399065661 is 166560993.

It can be written as a sum of positive squares in only one way, i.e., 201100761 + 197964900 = 14181^2 + 14070^2 .

It is not a de Polignac number, because 399065661 - 2⁷ = 399065533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399065621) 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, 22170306 + ... + 22170323.

It is an arithmetic number, because the mean of its divisors is an integer number (96071365).

Almost surely, 2^399065661 is an apocalyptic number.

It is an amenable number.

399065661 is a deficient number, since it is larger than the sum of its proper divisors (177362529).

399065661 is a wasteful number, since it uses less digits than its factorization.

399065661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44340635 (or 44340632 counting only the distinct ones).

The product of its (nonzero) digits is 262440, while the sum is 45.

The square root of 399065661 is about 19976.6278685868. The cubic root of 399065661 is about 736.2321634131.

The spelling of 399065661 in words is "three hundred ninety-nine million, sixty-five thousand, six hundred sixty-one".