399944807 has 4 divisors (see below), whose sum is σ = 400349376. Its totient is φ = 399540240.

The previous prime is 399944767. The next prime is 399944833. The reversal of 399944807 is 708449993.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 399944807 - 2¹⁸ = 399682663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399944107) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200798 + ... + 202779.

It is an arithmetic number, because the mean of its divisors is an integer number (100087344).

Almost surely, 2^399944807 is an apocalyptic number.

399944807 is a deficient number, since it is larger than the sum of its proper divisors (404569).

399944807 is an equidigital number, since it uses as much as digits as its factorization.

399944807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404568.

The product of its (nonzero) digits is 1959552, while the sum is 53.

The square root of 399944807 is about 19998.6201273988. The cubic root of 399944807 is about 736.7724093775.

The spelling of 399944807 in words is "three hundred ninety-nine million, nine hundred forty-four thousand, eight hundred seven".