399081217 has 4 divisors (see below), whose sum is σ = 402811056. Its totient is φ = 395351380.

The previous prime is 399081203. The next prime is 399081227. The reversal of 399081217 is 712180993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 712180993 = 23 ⋅30964391.

It is a cyclic number.

It is not a de Polignac number, because 399081217 - 2¹⁹ = 398556929 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 399081217.

It is not an unprimeable number, because it can be changed into a prime (399081227) 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, 1864759 + ... + 1864972.

It is an arithmetic number, because the mean of its divisors is an integer number (100702764).

Almost surely, 2^399081217 is an apocalyptic number.

It is an amenable number.

399081217 is a deficient number, since it is larger than the sum of its proper divisors (3729839).

399081217 is a wasteful number, since it uses less digits than its factorization.

399081217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3729838.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 399081217 is about 19977.0172197954. The cubic root of 399081217 is about 736.2417296573.

The spelling of 399081217 in words is "three hundred ninety-nine million, eighty-one thousand, two hundred seventeen".