28251815 has 4 divisors (see below), whose sum is σ = 33902184. Its totient is φ = 22601448.

The previous prime is 28251799. The next prime is 28251827. The reversal of 28251815 is 51815282.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51815282 = 2 ⋅25907641.

It is a cyclic number.

It is not a de Polignac number, because 28251815 - 2⁴ = 28251799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2825177 + ... + 2825186.

It is an arithmetic number, because the mean of its divisors is an integer number (8475546).

Almost surely, 2^28251815 is an apocalyptic number.

28251815 is a deficient number, since it is larger than the sum of its proper divisors (5650369).

28251815 is an equidigital number, since it uses as much as digits as its factorization.

28251815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5650368.

The product of its digits is 6400, while the sum is 32.

The square root of 28251815 is about 5315.2436444626. The cubic root of 28251815 is about 304.5664897410.

The spelling of 28251815 in words is "twenty-eight million, two hundred fifty-one thousand, eight hundred fifteen".