816573665 has 16 divisors (see below), whose sum is σ = 1049196240. Its totient is φ = 607918080.

The previous prime is 816573617. The next prime is 816573673. The reversal of 816573665 is 566375618.

It can be written as a sum of positive squares in 8 ways, for example, as 6431296 + 810142369 = 2536^2 + 28463^2 .

It is not a de Polignac number, because 816573665 - 2¹⁰ = 816572641 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46406 + ... + 61535.

It is an arithmetic number, because the mean of its divisors is an integer number (65574765).

Almost surely, 2^816573665 is an apocalyptic number.

816573665 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

816573665 is a deficient number, since it is larger than the sum of its proper divisors (232622575).

816573665 is a wasteful number, since it uses less digits than its factorization.

816573665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108052.

The product of its digits is 907200, while the sum is 47.

The square root of 816573665 is about 28575.7530959378. The cubic root of 816573665 is about 934.6846773370.

The spelling of 816573665 in words is "eight hundred sixteen million, five hundred seventy-three thousand, six hundred sixty-five".