28109181 has 4 divisors (see below), whose sum is σ = 37478912. Its totient is φ = 18739452.

The previous prime is 28109167. The next prime is 28109201. The reversal of 28109181 is 18190182.

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 28109181 - 2⁶ = 28109117 is a prime.

It is a super-2 number, since 2×28109181² = 1580252112981522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28109111) 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, 4684861 + ... + 4684866.

It is an arithmetic number, because the mean of its divisors is an integer number (9369728).

Almost surely, 2^28109181 is an apocalyptic number.

It is an amenable number.

28109181 is a deficient number, since it is larger than the sum of its proper divisors (9369731).

28109181 is an equidigital number, since it uses as much as digits as its factorization.

28109181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9369730.

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 28109181 is about 5301.8092195023. The cubic root of 28109181 is about 304.0530731726.

The spelling of 28109181 in words is "twenty-eight million, one hundred nine thousand, one hundred eighty-one".