165263991 has 8 divisors (see below), whose sum is σ = 220944240. Its totient is φ = 109879872.

The previous prime is 165263963. The next prime is 165263999. The reversal of 165263991 is 199362561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165263991 - 2⁷ = 165263863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165263999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 72726 + ... + 74963.

It is an arithmetic number, because the mean of its divisors is an integer number (27618030).

Almost surely, 2^165263991 is an apocalyptic number.

165263991 is a deficient number, since it is larger than the sum of its proper divisors (55680249).

165263991 is a wasteful number, since it uses less digits than its factorization.

165263991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148065.

The product of its digits is 87480, while the sum is 42.

The square root of 165263991 is about 12855.5043074941. The cubic root of 165263991 is about 548.7730124239.

The spelling of 165263991 in words is "one hundred sixty-five million, two hundred sixty-three thousand, nine hundred ninety-one".