399781820 has 24 divisors (see below), whose sum is σ = 868492800. Its totient is φ = 154398272.

The previous prime is 399781819. The next prime is 399781873. The reversal of 399781820 is 28187993.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 344060 + ... + 345219.

It is an arithmetic number, because the mean of its divisors is an integer number (36187200).

Almost surely, 2^399781820 is an apocalyptic number.

It is an amenable number.

399781820 is an abundant number, since it is smaller than the sum of its proper divisors (468710980).

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

399781820 is a wasteful number, since it uses less digits than its factorization.

399781820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 689317 (or 689315 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 47.

The square root of 399781820 is about 19994.5447560078. The cubic root of 399781820 is about 736.6723116985.

The spelling of 399781820 in words is "three hundred ninety-nine million, seven hundred eighty-one thousand, eight hundred twenty".