321261665 has 16 divisors (see below), whose sum is σ = 411143040. Its totient is φ = 240142080.

The previous prime is 321261607. The next prime is 321261679. The reversal of 321261665 is 566162123.

It is not a de Polignac number, because 321261665 - 2²⁸ = 52826209 is a prime.

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, 1781 + ... + 25410.

It is an arithmetic number, because the mean of its divisors is an integer number (25696440).

Almost surely, 2^321261665 is an apocalyptic number.

It is an amenable number.

321261665 is a deficient number, since it is larger than the sum of its proper divisors (89881375).

321261665 is a wasteful number, since it uses less digits than its factorization.

321261665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27352.

The product of its digits is 12960, while the sum is 32.

The square root of 321261665 is about 17923.7737376926. The cubic root of 321261665 is about 684.8881235230. Note that the first 3 decimals are identical.

The spelling of 321261665 in words is "three hundred twenty-one million, two hundred sixty-one thousand, six hundred sixty-five".