399969257 has 4 divisors (see below), whose sum is σ = 400593876. Its totient is φ = 399344640.

The previous prime is 399969239. The next prime is 399969289. The reversal of 399969257 is 752969993.

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 323424256 + 76545001 = 17984^2 + 8749^2 .

It is a cyclic number.

It is not a de Polignac number, because 399969257 - 2¹² = 399965161 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 399969196 and 399969205.

It is not an unprimeable number, because it can be changed into a prime (399966257) 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, 311348 + ... + 312629.

It is an arithmetic number, because the mean of its divisors is an integer number (100148469).

Almost surely, 2^399969257 is an apocalyptic number.

It is an amenable number.

399969257 is a deficient number, since it is larger than the sum of its proper divisors (624619).

399969257 is an equidigital number, since it uses as much as digits as its factorization.

399969257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 624618.

The product of its digits is 8266860, while the sum is 59.

The square root of 399969257 is about 19999.2314102317. The cubic root of 399969257 is about 736.7874228811.

The spelling of 399969257 in words is "three hundred ninety-nine million, nine hundred sixty-nine thousand, two hundred fifty-seven".