399666155265 has 40 divisors (see below), whose sum is σ = 771549260328. Its totient is φ = 196758720000.

The previous prime is 399666155261. The next prime is 399666155267. The reversal of 399666155265 is 562551666993.

It can be written as a sum of positive squares in 4 ways, for example, as 1324668816 + 398341486449 = 36396^2 + 631143^2 .

It is not a de Polignac number, because 399666155265 - 2² = 399666155261 is a prime.

It is not an unprimeable number, because it can be changed into a prime (399666155261) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 37949736 + ... + 37960265.

Almost surely, 2^399666155265 is an apocalyptic number.

It is an amenable number.

399666155265 is a deficient number, since it is larger than the sum of its proper divisors (371883105063).

399666155265 is a wasteful number, since it uses less digits than its factorization.

399666155265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75910031 (or 75910022 counting only the distinct ones).

The product of its digits is 78732000, while the sum is 63.

It can be divided in two parts, 399666 and 155265, that added together give a triangular number (554931 = T₁₀₅₃).

The spelling of 399666155265 in words is "three hundred ninety-nine billion, six hundred sixty-six million, one hundred fifty-five thousand, two hundred sixty-five".