28750521 has 4 divisors (see below), whose sum is σ = 38334032. Its totient is φ = 19167012.

The previous prime is 28750487. The next prime is 28750537. The reversal of 28750521 is 12505782.

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 a de Polignac number, because none of the positive numbers 2^k-28750521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28750541) 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, 4791751 + ... + 4791756.

It is an arithmetic number, because the mean of its divisors is an integer number (9583508).

Almost surely, 2^28750521 is an apocalyptic number.

It is an amenable number.

28750521 is a deficient number, since it is larger than the sum of its proper divisors (9583511).

28750521 is an equidigital number, since it uses as much as digits as its factorization.

28750521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9583510.

The product of its (nonzero) digits is 5600, while the sum is 30.

The square root of 28750521 is about 5361.9512306622. The cubic root of 28750521 is about 306.3481342594.

The spelling of 28750521 in words is "twenty-eight million, seven hundred fifty thousand, five hundred twenty-one".