399638529 has 14 divisors (see below), whose sum is σ = 599184786. Its totient is φ = 266425200.

The previous prime is 399638513. The next prime is 399638537. The reversal of 399638529 is 925836993.

It can be written as a sum of positive squares in only one way, i.e., 382124304 + 17514225 = 19548^2 + 4185^2 .

It is not a de Polignac number, because 399638529 - 2⁴ = 399638513 is a prime.

It is a super-2 number, since 2×399638529² = 319421907722567682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (399638929) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 273372 + ... + 274829.

It is a Proth number, since it is equal to 3049 ⋅ 2¹⁷ + 1 and 3049 < 2¹⁷.

Almost surely, 2^399638529 is an apocalyptic number.

It is an amenable number.

399638529 is a deficient number, since it is larger than the sum of its proper divisors (199546257).

399638529 is an frugal number, since it uses more digits than its factorization.

399638529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548219 (or 548204 counting only the distinct ones).

The product of its digits is 3149280, while the sum is 54.

The square root of 399638529 is about 19990.9611824945. The cubic root of 399638529 is about 736.5842877473.

The spelling of 399638529 in words is "three hundred ninety-nine million, six hundred thirty-eight thousand, five hundred twenty-nine".