165329991 has 20 divisors (see below), whose sum is σ = 248875704. Its totient is φ = 109371600.

The previous prime is 165329987. The next prime is 165330007. The reversal of 165329991 is 199923561.

It is a happy number.

It is not a de Polignac number, because 165329991 - 2² = 165329987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165329921) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2821 + ... + 18401.

Almost surely, 2^165329991 is an apocalyptic number.

165329991 is a deficient number, since it is larger than the sum of its proper divisors (83545713).

165329991 is a wasteful number, since it uses less digits than its factorization.

165329991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15724 (or 15715 counting only the distinct ones).

The product of its digits is 131220, while the sum is 45.

The square root of 165329991 is about 12858.0710450674. The cubic root of 165329991 is about 548.8460555556.

The spelling of 165329991 in words is "one hundred sixty-five million, three hundred twenty-nine thousand, nine hundred ninety-one".