28132109 has 4 divisors (see below), whose sum is σ = 28818300. Its totient is φ = 27445920.

The previous prime is 28132067. The next prime is 28132121. The reversal of 28132109 is 90123182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90123182 = 2 ⋅45061591.

It can be written as a sum of positive squares in 2 ways, for example, as 4609609 + 23522500 = 2147^2 + 4850^2 .

It is a cyclic number.

It is not a de Polignac number, because 28132109 - 2⁸ = 28131853 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 (28132129) 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, 343034 + ... + 343115.

It is an arithmetic number, because the mean of its divisors is an integer number (7204575).

Almost surely, 2^28132109 is an apocalyptic number.

It is an amenable number.

28132109 is a deficient number, since it is larger than the sum of its proper divisors (686191).

28132109 is an equidigital number, since it uses as much as digits as its factorization.

28132109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686190.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 28132109 is about 5303.9710594987. The cubic root of 28132109 is about 304.1357203603.

The spelling of 28132109 in words is "twenty-eight million, one hundred thirty-two thousand, one hundred nine".