399565 has 8 divisors (see below), whose sum is σ = 483480. Its totient is φ = 316992.

The previous prime is 399557. The next prime is 399571. The reversal of 399565 is 565993.

It can be written as a sum of positive squares in 4 ways, for example, as 56169 + 343396 = 237^2 + 586^2 .

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 399565 - 2³ = 399557 is a prime.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 531 + ... + 1039.

It is an arithmetic number, because the mean of its divisors is an integer number (60435).

2³⁹⁹⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

399565 is a deficient number, since it is larger than the sum of its proper divisors (83915).

399565 is a wasteful number, since it uses less digits than its factorization.

399565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671.

The product of its digits is 36450, while the sum is 37.

The square root of 399565 is about 632.1115407901. Note that the first 3 decimals coincide. The cubic root of 399565 is about 73.6539110565.

It can be divided in two parts, 39 and 9565, that added together give a square (9604 = 98²).

The spelling of 399565 in words is "three hundred ninety-nine thousand, five hundred sixty-five".