165135981 has 16 divisors (see below), whose sum is σ = 222992000. Its totient is φ = 108692928.

The previous prime is 165135979. The next prime is 165136003. The reversal of 165135981 is 189531561.

It is not a de Polignac number, because 165135981 - 2¹ = 165135979 is a prime.

It is a super-2 number, since 2×165135981² = 54539784441664722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165135911) 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 15 ways as a sum of consecutive naturals, for example, 113400 + ... + 114846.

It is an arithmetic number, because the mean of its divisors is an integer number (13937000).

Almost surely, 2^165135981 is an apocalyptic number.

It is an amenable number.

165135981 is a deficient number, since it is larger than the sum of its proper divisors (57856019).

165135981 is a wasteful number, since it uses less digits than its factorization.

165135981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1908.

The product of its digits is 32400, while the sum is 39.

The square root of 165135981 is about 12850.5245418232. The cubic root of 165135981 is about 548.6312864932.

The spelling of 165135981 in words is "one hundred sixty-five million, one hundred thirty-five thousand, nine hundred eighty-one".