165565520 has 20 divisors (see below), whose sum is σ = 384940020. Its totient is φ = 66226176.

The previous prime is 165565511. The next prime is 165565531. The reversal of 165565520 is 25565561.

It can be written as a sum of positive squares in 2 ways, for example, as 43507216 + 122058304 = 6596^2 + 11048^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1034705 + ... + 1034864.

It is an arithmetic number, because the mean of its divisors is an integer number (19247001).

Almost surely, 2^165565520 is an apocalyptic number.

165565520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165565520 is an abundant number, since it is smaller than the sum of its proper divisors (219374500).

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

165565520 is a wasteful number, since it uses less digits than its factorization.

165565520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2069582 (or 2069576 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 35.

The square root of 165565520 is about 12867.2265853990. The cubic root of 165565520 is about 549.1065604703.

The spelling of 165565520 in words is "one hundred sixty-five million, five hundred sixty-five thousand, five hundred twenty".