399138521 has 8 divisors (see below), whose sum is σ = 402991104. Its totient is φ = 395297280.

The previous prime is 399138511. The next prime is 399138577. The reversal of 399138521 is 125831993.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 399138521 - 2⁶ = 399138457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399138511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78956 + ... + 83858.

It is an arithmetic number, because the mean of its divisors is an integer number (50373888).

Almost surely, 2^399138521 is an apocalyptic number.

It is an amenable number.

399138521 is a deficient number, since it is larger than the sum of its proper divisors (3852583).

399138521 is a wasteful number, since it uses less digits than its factorization.

399138521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5671.

The product of its digits is 58320, while the sum is 41.

The square root of 399138521 is about 19978.4514164637. The cubic root of 399138521 is about 736.2769669099.

The spelling of 399138521 in words is "three hundred ninety-nine million, one hundred thirty-eight thousand, five hundred twenty-one".