165531555 has 72 divisors (see below), whose sum is σ = 342093024. Its totient is φ = 73785600.

The previous prime is 165531551. The next prime is 165531577. The reversal of 165531555 is 555135561.

It is not a de Polignac number, because 165531555 - 2² = 165531551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165531551) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 89490 + ... + 91320.

It is an arithmetic number, because the mean of its divisors is an integer number (4751292).

Almost surely, 2^165531555 is an apocalyptic number.

165531555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

165531555 is an abundant number, since it is smaller than the sum of its proper divisors (176561469).

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

165531555 is a wasteful number, since it uses less digits than its factorization.

165531555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1897 (or 1887 counting only the distinct ones).

The product of its digits is 56250, while the sum is 36.

The square root of 165531555 is about 12865.9066917182. The cubic root of 165531555 is about 549.0690090126.

The spelling of 165531555 in words is "one hundred sixty-five million, five hundred thirty-one thousand, five hundred fifty-five".