399816918 has 32 divisors (see below), whose sum is σ = 889480800. Its totient is φ = 133122528.

The previous prime is 399816917. The next prime is 399816919. The reversal of 399816918 is 819618993.

It is an interprime number because it is at equal distance from previous prime (399816917) and next prime (399816919).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399816917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51048 + ... + 58356.

It is an arithmetic number, because the mean of its divisors is an integer number (27796275).

Almost surely, 2^399816918 is an apocalyptic number.

399816918 is an abundant number, since it is smaller than the sum of its proper divisors (489663882).

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

399816918 is a wasteful number, since it uses less digits than its factorization.

399816918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8333 (or 8327 counting only the distinct ones).

The product of its digits is 839808, while the sum is 54.

The square root of 399816918 is about 19995.4224261454. The cubic root of 399816918 is about 736.6938692639.

The spelling of 399816918 in words is "three hundred ninety-nine million, eight hundred sixteen thousand, nine hundred eighteen".