28165181 has 4 divisors (see below), whose sum is σ = 30725664. Its totient is φ = 25604700.

The previous prime is 28165169. The next prime is 28165187. The reversal of 28165181 is 18156182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 28165181 - 2⁶ = 28165117 is a prime.

It is a super-2 number, since 2×28165181² = 1586554841525522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28165187) 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, 1280225 + ... + 1280246.

It is an arithmetic number, because the mean of its divisors is an integer number (7681416).

Almost surely, 2^28165181 is an apocalyptic number.

It is an amenable number.

28165181 is a deficient number, since it is larger than the sum of its proper divisors (2560483).

28165181 is a wasteful number, since it uses less digits than its factorization.

28165181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2560482.

The product of its digits is 3840, while the sum is 32.

The square root of 28165181 is about 5307.0878078283. The cubic root of 28165181 is about 304.2548539523.

It can be divided in two parts, 2816 and 5181, that added together give a palindrome (7997).

The spelling of 28165181 in words is "twenty-eight million, one hundred sixty-five thousand, one hundred eighty-one".