28639251 has 24 divisors (see below), whose sum is σ = 45165120. Its totient is φ = 18085032.

The previous prime is 28639231. The next prime is 28639267. The reversal of 28639251 is 15293682.

It is not a de Polignac number, because 28639251 - 2⁷ = 28639123 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28639231) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1516 + ... + 7718.

It is an arithmetic number, because the mean of its divisors is an integer number (1881880).

Almost surely, 2^28639251 is an apocalyptic number.

28639251 is a deficient number, since it is larger than the sum of its proper divisors (16525869).

28639251 is an equidigital number, since it uses as much as digits as its factorization.

28639251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6237 (or 6225 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 28639251 is about 5351.5652850358. The cubic root of 28639251 is about 305.9524147459.

The spelling of 28639251 in words is "twenty-eight million, six hundred thirty-nine thousand, two hundred fifty-one".