28987891 has 8 divisors (see below), whose sum is σ = 29755440. Its totient is φ = 28224672.

The previous prime is 28987867. The next prime is 28987897. The reversal of 28987891 is 19878982.

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

It is a cyclic number.

It is not a de Polignac number, because 28987891 - 2⁵ = 28987859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28987897) 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, 15861 + ... + 17593.

It is an arithmetic number, because the mean of its divisors is an integer number (3719430).

Almost surely, 2^28987891 is an apocalyptic number.

28987891 is a deficient number, since it is larger than the sum of its proper divisors (767549).

28987891 is a wasteful number, since it uses less digits than its factorization.

28987891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2165.

The product of its digits is 580608, while the sum is 52.

The square root of 28987891 is about 5384.0403973224. The cubic root of 28987891 is about 307.1889149092.

The spelling of 28987891 in words is "twenty-eight million, nine hundred eighty-seven thousand, eight hundred ninety-one".