399942407 has 4 divisors (see below), whose sum is σ = 400012200. Its totient is φ = 399872616.

The previous prime is 399942401. The next prime is 399942443. The reversal of 399942407 is 704249993.

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 399942407 - 2¹⁸ = 399680263 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 (399942401) 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, 25448 + ... + 38045.

It is an arithmetic number, because the mean of its divisors is an integer number (100003050).

Almost surely, 2^399942407 is an apocalyptic number.

399942407 is a deficient number, since it is larger than the sum of its proper divisors (69793).

399942407 is an equidigital number, since it uses as much as digits as its factorization.

399942407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69792.

The product of its (nonzero) digits is 489888, while the sum is 47.

The square root of 399942407 is about 19998.5601231689. The cubic root of 399942407 is about 736.7709356264.

The spelling of 399942407 in words is "three hundred ninety-nine million, nine hundred forty-two thousand, four hundred seven".