165997281 has 32 divisors (see below), whose sum is σ = 247091200. Its totient is φ = 98677440.

The previous prime is 165997277. The next prime is 165997289. The reversal of 165997281 is 182799561.

It is not a de Polignac number, because 165997281 - 2² = 165997277 is a prime.

It is a super-2 number, since 2×165997281² = 55110194598785922, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 165997281.

It is not an unprimeable number, because it can be changed into a prime (165997289) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 64110 + ... + 66648.

It is an arithmetic number, because the mean of its divisors is an integer number (7721600).

Almost surely, 2^165997281 is an apocalyptic number.

It is an amenable number.

165997281 is a deficient number, since it is larger than the sum of its proper divisors (81093919).

165997281 is a wasteful number, since it uses less digits than its factorization.

165997281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2629.

The product of its digits is 272160, while the sum is 48.

The square root of 165997281 is about 12883.9932086291. The cubic root of 165997281 is about 549.5834653393.

The spelling of 165997281 in words is "one hundred sixty-five million, nine hundred ninety-seven thousand, two hundred eighty-one".