28640225 has 12 divisors (see below), whose sum is σ = 35613420. Its totient is φ = 22848000.

The previous prime is 28640207. The next prime is 28640231. The reversal of 28640225 is 52204682.

It can be written as a sum of positive squares in 6 ways, for example, as 327184 + 28313041 = 572^2 + 5321^2 .

It is not a de Polignac number, because 28640225 - 2⁸ = 28639969 is a prime.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8825 + ... + 11625.

It is an arithmetic number, because the mean of its divisors is an integer number (2967785).

Almost surely, 2^28640225 is an apocalyptic number.

28640225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

28640225 is a deficient number, since it is larger than the sum of its proper divisors (6973195).

28640225 is a wasteful number, since it uses less digits than its factorization.

28640225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3220 (or 3215 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 29.

The square root of 28640225 is about 5351.6562856746. The cubic root of 28640225 is about 305.9558831126.

The spelling of 28640225 in words is "twenty-eight million, six hundred forty thousand, two hundred twenty-five".