399905 has 12 divisors (see below), whose sum is σ = 528276. Its totient is φ = 290400.

The previous prime is 399899. The next prime is 399911. The reversal of 399905 is 509993.

It is an interprime number because it is at equal distance from previous prime (399899) and next prime (399911).

It can be written as a sum of positive squares in 2 ways, for example, as 234256 + 165649 = 484^2 + 407^2 .

It is not a de Polignac number, because 399905 - 2¹⁴ = 383521 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 275 + ... + 935.

It is an arithmetic number, because the mean of its divisors is an integer number (44023).

2³⁹⁹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

399905 is a deficient number, since it is larger than the sum of its proper divisors (128371).

399905 is a wasteful number, since it uses less digits than its factorization.

399905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688 (or 677 counting only the distinct ones).

The product of its (nonzero) digits is 10935, while the sum is 35.

The square root of 399905 is about 632.3804234794. The cubic root of 399905 is about 73.6747964611.

The spelling of 399905 in words is "three hundred ninety-nine thousand, nine hundred five".