28781987 has 8 divisors (see below), whose sum is σ = 31110240. Its totient is φ = 26470080.

The previous prime is 28781971. The next prime is 28782031. The reversal of 28781987 is 78918782.

It is a happy number.

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

It is not a de Polignac number, because 28781987 - 2⁴ = 28781971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28781917) 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, 287 + ... + 7592.

It is an arithmetic number, because the mean of its divisors is an integer number (3888780).

Almost surely, 2^28781987 is an apocalyptic number.

28781987 is a deficient number, since it is larger than the sum of its proper divisors (2328253).

28781987 is a wasteful number, since it uses less digits than its factorization.

28781987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8173.

The product of its digits is 451584, while the sum is 50.

The square root of 28781987 is about 5364.8846213129. The cubic root of 28781987 is about 306.4598543897.

The spelling of 28781987 in words is "twenty-eight million, seven hundred eighty-one thousand, nine hundred eighty-seven".