28312500 has 84 divisors (see below), whose sum is σ = 83123936. Its totient is φ = 7500000.

The previous prime is 28312499. The next prime is 28312561. The reversal of 28312500 is 521382.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 187425 + ... + 187575.

Almost surely, 2^28312500 is an apocalyptic number.

28312500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28312500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41561968).

28312500 is an abundant number, since it is smaller than the sum of its proper divisors (54811436).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28312500 is an equidigital number, since it uses as much as digits as its factorization.

28312500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 161 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 28312500 is about 5320.9491634482. The cubic root of 28312500 is about 304.7844037597.

Adding to 28312500 its reverse (521382), we get a palindrome (28833882).

The spelling of 28312500 in words is "twenty-eight million, three hundred twelve thousand, five hundred".