399121 has 4 divisors (see below), whose sum is σ = 400932. Its totient is φ = 397312.

The previous prime is 399107. The next prime is 399131. The reversal of 399121 is 121993.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 239121 + 160000 = 489^2 + 400^2 .

It is a cyclic number.

It is not a de Polignac number, because 399121 - 2⁹ = 398609 is a prime.

It is a Duffinian number.

399121 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399101) 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, 520 + ... + 1033.

It is an arithmetic number, because the mean of its divisors is an integer number (100233).

2³⁹⁹¹²¹ is an apocalyptic number.

It is an amenable number.

399121 is a deficient number, since it is larger than the sum of its proper divisors (1811).

399121 is a wasteful number, since it uses less digits than its factorization.

399121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1810.

The product of its digits is 486, while the sum is 25.

The square root of 399121 is about 631.7602393313. The cubic root of 399121 is about 73.6266193292.

The spelling of 399121 in words is "three hundred ninety-nine thousand, one hundred twenty-one".