28213915 has 4 divisors (see below), whose sum is σ = 33856704. Its totient is φ = 22571128.

The previous prime is 28213907. The next prime is 28213919. The reversal of 28213915 is 51931282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28213915 - 2³ = 28213907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28213919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2821387 + ... + 2821396.

It is an arithmetic number, because the mean of its divisors is an integer number (8464176).

Almost surely, 2^28213915 is an apocalyptic number.

28213915 is a deficient number, since it is larger than the sum of its proper divisors (5642789).

28213915 is an equidigital number, since it uses as much as digits as its factorization.

28213915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5642788.

The product of its digits is 4320, while the sum is 31.

The square root of 28213915 is about 5311.6772304047. The cubic root of 28213915 is about 304.4302361291.

The spelling of 28213915 in words is "twenty-eight million, two hundred thirteen thousand, nine hundred fifteen".