399720881 has 24 divisors (see below), whose sum is σ = 494121600. Its totient is φ = 322233408.

The previous prime is 399720877. The next prime is 399720883. The reversal of 399720881 is 188027993.

It is not a de Polignac number, because 399720881 - 2² = 399720877 is a prime.

It is a super-2 number, since 2×399720881² = 319553565414832322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399720883) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 285020 + ... + 286418.

It is an arithmetic number, because the mean of its divisors is an integer number (20588400).

Almost surely, 2^399720881 is an apocalyptic number.

It is an amenable number.

399720881 is a deficient number, since it is larger than the sum of its proper divisors (94400719).

399720881 is an frugal number, since it uses more digits than its factorization.

399720881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1451 (or 1423 counting only the distinct ones).

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

The square root of 399720881 is about 19993.0208072717. The cubic root of 399720881 is about 736.6348793183.

The spelling of 399720881 in words is "three hundred ninety-nine million, seven hundred twenty thousand, eight hundred eighty-one".