28257191 has 4 divisors (see below), whose sum is σ = 28430712. Its totient is φ = 28083672.

The previous prime is 28257169. The next prime is 28257197. The reversal of 28257191 is 19175282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28257191 - 2¹⁸ = 27995047 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28257197) 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, 86516 + ... + 86841.

It is an arithmetic number, because the mean of its divisors is an integer number (7107678).

Almost surely, 2^28257191 is an apocalyptic number.

28257191 is a deficient number, since it is larger than the sum of its proper divisors (173521).

28257191 is a wasteful number, since it uses less digits than its factorization.

28257191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173520.

The product of its digits is 10080, while the sum is 35.

The square root of 28257191 is about 5315.7493357005. The cubic root of 28257191 is about 304.5858070321.

The spelling of 28257191 in words is "twenty-eight million, two hundred fifty-seven thousand, one hundred ninety-one".