399669121 has 4 divisors (see below), whose sum is σ = 399732912. Its totient is φ = 399605332.

The previous prime is 399669119. The next prime is 399669157. The reversal of 399669121 is 121966993.

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: 121966993 = 17 ⋅7174529.

It is a cyclic number.

It is not a de Polignac number, because 399669121 - 2¹ = 399669119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399669421) 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, 21331 + ... + 35416.

It is an arithmetic number, because the mean of its divisors is an integer number (99933228).

Almost surely, 2^399669121 is an apocalyptic number.

It is an amenable number.

399669121 is a deficient number, since it is larger than the sum of its proper divisors (63791).

399669121 is an equidigital number, since it uses as much as digits as its factorization.

399669121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63790.

The product of its digits is 157464, while the sum is 46.

The square root of 399669121 is about 19991.7263136529. The cubic root of 399669121 is about 736.6030822411.

The spelling of 399669121 in words is "three hundred ninety-nine million, six hundred sixty-nine thousand, one hundred twenty-one".