399905778 has 16 divisors (see below), whose sum is σ = 800948160. Its totient is φ = 133112496.

The previous prime is 399905767. The next prime is 399905783. The reversal of 399905778 is 877509993.

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 42750 + ... + 51257.

It is an arithmetic number, because the mean of its divisors is an integer number (50059260).

Almost surely, 2^399905778 is an apocalyptic number.

399905778 is an abundant number, since it is smaller than the sum of its proper divisors (401042382).

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

399905778 is a wasteful number, since it uses less digits than its factorization.

399905778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94721.

The product of its (nonzero) digits is 4286520, while the sum is 57.

The square root of 399905778 is about 19997.6443112683. The cubic root of 399905778 is about 736.7484423823.

The spelling of 399905778 in words is "three hundred ninety-nine million, nine hundred five thousand, seven hundred seventy-eight".