165521265 has 96 divisors (see below), whose sum is σ = 351630720. Its totient is φ = 65673216.

The previous prime is 165521261. The next prime is 165521303. The reversal of 165521265 is 562125561.

165521265 = 378² + 379² + ... + 819².

It is not a de Polignac number, because 165521265 - 2² = 165521261 is a prime.

It is a super-3 number, since 3×165521265³ (a number of 26 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (165521261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 161926 + ... + 162944.

It is an arithmetic number, because the mean of its divisors is an integer number (3662820).

Almost surely, 2^165521265 is an apocalyptic number.

165521265 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

165521265 is an abundant number, since it is smaller than the sum of its proper divisors (186109455).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

165521265 is a wasteful number, since it uses less digits than its factorization.

165521265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071 (or 1064 counting only the distinct ones).

The product of its digits is 18000, while the sum is 33.

The square root of 165521265 is about 12865.5067914171. The cubic root of 165521265 is about 549.0576314495.

The spelling of 165521265 in words is "one hundred sixty-five million, five hundred twenty-one thousand, two hundred sixty-five".