20165 has 8 divisors (see below), whose sum is σ = 25080. Its totient is φ = 15552.

The previous prime is 20161. The next prime is 20173. The reversal of 20165 is 56102.

It is a Cunningham number, because it is equal to 142²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 7396 + 12769 = 86^2 + 113^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20165 - 2² = 20161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20161) 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, 131 + ... + 239.

It is an arithmetic number, because the mean of its divisors is an integer number (3135).

2²⁰¹⁶⁵ is an apocalyptic number.

It is an amenable number.

20165 is a deficient number, since it is larger than the sum of its proper divisors (4915).

20165 is a wasteful number, since it uses less digits than its factorization.

20165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 20165 is about 142.0035210831. The cubic root of 20165 is about 27.2186183083.

Adding to 20165 its reverse (56102), we get a palindrome (76267).

Subtracting 20165 from its reverse (56102), we obtain a cube (35937 = 33³).

The spelling of 20165 in words is "twenty thousand, one hundred sixty-five".