399663 has 18 divisors (see below), whose sum is σ = 636272. Its totient is φ = 241560.

The previous prime is 399647. The next prime is 399667. The reversal of 399663 is 366993.

It is not a de Polignac number, because 399663 - 2⁴ = 399647 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 (399667) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 906 + ... + 1272.

2³⁹⁹⁶⁶³ is an apocalyptic number.

399663 is a gapful number since it is divisible by the number (33) formed by its first and last digit.

399663 is a deficient number, since it is larger than the sum of its proper divisors (236609).

399663 is a wasteful number, since it uses less digits than its factorization.

399663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 395 (or 381 counting only the distinct ones).

The product of its digits is 26244, while the sum is 36.

The square root of 399663 is about 632.1890540020. The cubic root of 399663 is about 73.6599321822.

The spelling of 399663 in words is "three hundred ninety-nine thousand, six hundred sixty-three".