399121081 has 4 divisors (see below), whose sum is σ = 399230964. Its totient is φ = 399011200.

The previous prime is 399121061. The next prime is 399121091. The reversal of 399121081 is 180121993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 180121993 = 23 ⋅7831391.

It can be written as a sum of positive squares in 2 ways, for example, as 268796025 + 130325056 = 16395^2 + 11416^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399121081 is a prime.

It is a super-2 number, since 2×399121081² = 318595274597217122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399121061) 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, 49300 + ... + 56821.

It is an arithmetic number, because the mean of its divisors is an integer number (99807741).

Almost surely, 2^399121081 is an apocalyptic number.

It is an amenable number.

399121081 is a deficient number, since it is larger than the sum of its proper divisors (109883).

399121081 is a wasteful number, since it uses less digits than its factorization.

399121081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109882.

The product of its (nonzero) digits is 3888, while the sum is 34.

The square root of 399121081 is about 19978.0149414300. The cubic root of 399121081 is about 736.2662430996.

The spelling of 399121081 in words is "three hundred ninety-nine million, one hundred twenty-one thousand, eighty-one".