165993905 has 16 divisors (see below), whose sum is σ = 248344704. Its totient is φ = 103476480.

The previous prime is 165993901. The next prime is 165993913. The reversal of 165993905 is 509399561.

It is not a de Polignac number, because 165993905 - 2² = 165993901 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165993905.

It is not an unprimeable number, because it can be changed into a prime (165993901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 215192 + ... + 215961.

It is an arithmetic number, because the mean of its divisors is an integer number (15521544).

Almost surely, 2^165993905 is an apocalyptic number.

It is an amenable number.

165993905 is a deficient number, since it is larger than the sum of its proper divisors (82350799).

165993905 is a wasteful number, since it uses less digits than its factorization.

165993905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431176.

The product of its (nonzero) digits is 328050, while the sum is 47.

The square root of 165993905 is about 12883.8621926812. The cubic root of 165993905 is about 549.5797395627.

The spelling of 165993905 in words is "one hundred sixty-five million, nine hundred ninety-three thousand, nine hundred five".