399220555 has 4 divisors (see below), whose sum is σ = 479064672. Its totient is φ = 319376440.

The previous prime is 399220543. The next prime is 399220559. The reversal of 399220555 is 555022993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 555022993 = 7 ⋅79288999.

It is not a de Polignac number, because 399220555 - 2⁹ = 399220043 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 not an unprimeable number, because it can be changed into a prime (399220559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39922051 + ... + 39922060.

It is an arithmetic number, because the mean of its divisors is an integer number (119766168).

Almost surely, 2^399220555 is an apocalyptic number.

399220555 is a deficient number, since it is larger than the sum of its proper divisors (79844117).

399220555 is an equidigital number, since it uses as much as digits as its factorization.

399220555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79844116.

The product of its (nonzero) digits is 121500, while the sum is 40.

The square root of 399220555 is about 19980.5043730132. The cubic root of 399220555 is about 736.3274052114.

The spelling of 399220555 in words is "three hundred ninety-nine million, two hundred twenty thousand, five hundred fifty-five".