399999990 has 32 divisors (see below), whose sum is σ = 1033847136. Its totient is φ = 98461440.

The previous prime is 399999959. The next prime is 400000009. The reversal of 399999990 is 99999993.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 512431 + ... + 513210.

It is an arithmetic number, because the mean of its divisors is an integer number (32307723).

Almost surely, 2^399999990 is an apocalyptic number.

399999990 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

399999990 is an abundant number, since it is smaller than the sum of its proper divisors (633847146).

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

399999990 is a wasteful number, since it uses less digits than its factorization.

399999990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1025664.

The product of its (nonzero) digits is 14348907, while the sum is 66.

The square root of 399999990 is about 19999.9997500000. Note that the first 3 decimals coincide. The cubic root of 399999990 is about 736.8062935880.

The spelling of 399999990 in words is "three hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety".