399263661 has 20 divisors (see below), whose sum is σ = 597638844. Its totient is φ = 265636800.

The previous prime is 399263659. The next prime is 399263713. The reversal of 399263661 is 166362993.

It is a happy number.

399263661 is a `hidden beast` number, since 3 + 9 + 9 + 2 + 636 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 208658025 + 190605636 = 14445^2 + 13806^2 .

It is not a de Polignac number, because 399263661 - 2¹ = 399263659 is a prime.

It is a super-2 number, since 2×399263661² = 318822941990245842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399263611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 37471 + ... + 46931.

Almost surely, 2^399263661 is an apocalyptic number.

It is an amenable number.

399263661 is a deficient number, since it is larger than the sum of its proper divisors (198375183).

399263661 is an equidigital number, since it uses as much as digits as its factorization.

399263661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9994 (or 9985 counting only the distinct ones).

The product of its digits is 314928, while the sum is 45.

The square root of 399263661 is about 19981.5830453946. The cubic root of 399263661 is about 736.3539060069.

The spelling of 399263661 in words is "three hundred ninety-nine million, two hundred sixty-three thousand, six hundred sixty-one".