165661533 has 12 divisors (see below), whose sum is σ = 240815068. Its totient is φ = 109736640.

The previous prime is 165661523. The next prime is 165661537. The reversal of 165661533 is 335166561.

165661533 is a `hidden beast` number, since 1 + 6 + 5 + 6 + 615 + 33 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 29192409 + 136469124 = 5403^2 + 11682^2 .

It is not a de Polignac number, because 165661533 - 2⁵ = 165661501 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165661537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57208 + ... + 60033.

Almost surely, 2^165661533 is an apocalyptic number.

It is an amenable number.

165661533 is a deficient number, since it is larger than the sum of its proper divisors (75153535).

165661533 is a wasteful number, since it uses less digits than its factorization.

165661533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117404 (or 117401 counting only the distinct ones).

The product of its digits is 48600, while the sum is 36.

The square root of 165661533 is about 12870.9569574294. The cubic root of 165661533 is about 549.2126839761.

The spelling of 165661533 in words is "one hundred sixty-five million, six hundred sixty-one thousand, five hundred thirty-three".