399987 has 18 divisors (see below), whose sum is σ = 672828. Its totient is φ = 228312.

The previous prime is 399983. The next prime is 399989. The reversal of 399987 is 789993.

It is a happy number.

It is not a de Polignac number, because 399987 - 2² = 399983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (399983) 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, 13 + ... + 894.

2³⁹⁹⁹⁸⁷ is an apocalyptic number.

399987 is a deficient number, since it is larger than the sum of its proper divisors (272841).

399987 is a wasteful number, since it uses less digits than its factorization.

399987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927 (or 917 counting only the distinct ones).

The product of its digits is 122472, while the sum is 45.

The square root of 399987 is about 632.4452545478. The cubic root of 399987 is about 73.6798317573.

The spelling of 399987 in words is "three hundred ninety-nine thousand, nine hundred eighty-seven".