399881 has 4 divisors (see below), whose sum is σ = 413700. Its totient is φ = 386064.

The previous prime is 399871. The next prime is 399887. The reversal of 399881 is 188993.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 319225 + 80656 = 565^2 + 284^2 .

It is a cyclic number.

It is not a de Polignac number, because 399881 - 2¹⁰ = 398857 is a prime.

It is a super-2 number, since 2×399881² = 319809628322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399887) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 6866 + ... + 6923.

It is an arithmetic number, because the mean of its divisors is an integer number (103425).

2³⁹⁹⁸⁸¹ is an apocalyptic number.

It is an amenable number.

399881 is a deficient number, since it is larger than the sum of its proper divisors (13819).

399881 is a wasteful number, since it uses less digits than its factorization.

399881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13818.

The product of its digits is 15552, while the sum is 38.

The square root of 399881 is about 632.3614472752. The cubic root of 399881 is about 73.6733225856.

The spelling of 399881 in words is "three hundred ninety-nine thousand, eight hundred eighty-one".