28720325 has 24 divisors (see below), whose sum is σ = 37248360. Its totient is φ = 21945600.

The previous prime is 28720313. The next prime is 28720331. The reversal of 28720325 is 52302782.

It can be written as a sum of positive squares in 12 ways, for example, as 5207524 + 23512801 = 2282^2 + 4849^2 .

It is not a de Polignac number, because 28720325 - 2¹⁶ = 28654789 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56171 + ... + 56679.

It is an arithmetic number, because the mean of its divisors is an integer number (1552015).

Almost surely, 2^28720325 is an apocalyptic number.

28720325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

28720325 is a deficient number, since it is larger than the sum of its proper divisors (8528035).

28720325 is a wasteful number, since it uses less digits than its factorization.

28720325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 617 (or 612 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 28720325 is about 5359.1347249346. The cubic root of 28720325 is about 306.2408465958.

The spelling of 28720325 in words is "twenty-eight million, seven hundred twenty thousand, three hundred twenty-five".