399690 has 24 divisors (see below), whose sum is σ = 1039428. Its totient is φ = 106560.

The previous prime is 399689. The next prime is 399691. The reversal of 399690 is 96993.

It is an interprime number because it is at equal distance from previous prime (399689) and next prime (399691).

It can be written as a sum of positive squares in 2 ways, for example, as 393129 + 6561 = 627^2 + 81^2 .

It is a super-2 number, since 2×399690² = 319504192200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (399691) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2131 + ... + 2310.

2³⁹⁹⁶⁹⁰ is an apocalyptic number.

399690 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

399690 is an abundant number, since it is smaller than the sum of its proper divisors (639738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399690 is a wasteful number, since it uses less digits than its factorization.

399690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4454 (or 4451 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The square root of 399690 is about 632.2104080130. The cubic root of 399690 is about 73.6615908908.

It can be divided in two parts, 399 and 690, that added together give a square (1089 = 33²).

The spelling of 399690 in words is "three hundred ninety-nine thousand, six hundred ninety".