399840015 has 32 divisors (see below), whose sum is σ = 675772416. Its totient is φ = 201559680.

The previous prime is 399840011. The next prime is 399840029. The reversal of 399840015 is 510048993.

It is a Cunningham number, because it is equal to 19996²-1.

It is not a de Polignac number, because 399840015 - 2² = 399840011 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399840011) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9997 + ... + 29993.

It is an arithmetic number, because the mean of its divisors is an integer number (21117888).

Almost surely, 2^399840015 is an apocalyptic number.

399840015 is a deficient number, since it is larger than the sum of its proper divisors (275932401).

399840015 is a wasteful number, since it uses less digits than its factorization.

399840015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20079.

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 399840015 is about 19995.9999749950. Note that the first 4 decimals coincide. The cubic root of 399840015 is about 736.7080549990.

The spelling of 399840015 in words is "three hundred ninety-nine million, eight hundred forty thousand, fifteen".