165721265 has 8 divisors (see below), whose sum is σ = 202236480. Its totient is φ = 130329712.

The previous prime is 165721229. The next prime is 165721267. The reversal of 165721265 is 562127561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 165721265 - 2¹⁴ = 165704881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165721267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 280589 + ... + 281178.

It is an arithmetic number, because the mean of its divisors is an integer number (25279560).

Almost surely, 2^165721265 is an apocalyptic number.

It is an amenable number.

165721265 is a deficient number, since it is larger than the sum of its proper divisors (36515215).

165721265 is an equidigital number, since it uses as much as digits as its factorization.

165721265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 561831.

The product of its digits is 25200, while the sum is 35.

The square root of 165721265 is about 12873.2771662852. The cubic root of 165721265 is about 549.2786852768.

It can be divided in two parts, 1657 and 21265, that added together give a palindrome (22922).

The spelling of 165721265 in words is "one hundred sixty-five million, seven hundred twenty-one thousand, two hundred sixty-five".