165399901 has 4 divisors (see below), whose sum is σ = 165644892. Its totient is φ = 165154912.

The previous prime is 165399889. The next prime is 165399907. The reversal of 165399901 is 109993561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 77528025 + 87871876 = 8805^2 + 9374^2 .

It is a cyclic number.

It is not a de Polignac number, because 165399901 - 2⁵ = 165399869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165399907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121480 + ... + 122833.

It is an arithmetic number, because the mean of its divisors is an integer number (41411223).

Almost surely, 2^165399901 is an apocalyptic number.

It is an amenable number.

165399901 is a deficient number, since it is larger than the sum of its proper divisors (244991).

165399901 is an equidigital number, since it uses as much as digits as its factorization.

165399901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244990.

The product of its (nonzero) digits is 65610, while the sum is 43.

The square root of 165399901 is about 12860.7892837104. The cubic root of 165399901 is about 548.9234047418.

The spelling of 165399901 in words is "one hundred sixty-five million, three hundred ninety-nine thousand, nine hundred one".