28128291 has 8 divisors (see below), whose sum is σ = 37534800. Its totient is φ = 18736992.

The previous prime is 28128271. The next prime is 28128307. The reversal of 28128291 is 19282182.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28128291 - 2⁹ = 28127779 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28128211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1621 + ... + 7673.

It is an arithmetic number, because the mean of its divisors is an integer number (4691850).

Almost surely, 2^28128291 is an apocalyptic number.

28128291 is a deficient number, since it is larger than the sum of its proper divisors (9406509).

28128291 is a wasteful number, since it uses less digits than its factorization.

28128291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7605.

The product of its digits is 4608, while the sum is 33.

The square root of 28128291 is about 5303.6111282785. The cubic root of 28128291 is about 304.1219609615.

The spelling of 28128291 in words is "twenty-eight million, one hundred twenty-eight thousand, two hundred ninety-one".