28987391 has 16 divisors (see below), whose sum is σ = 30935040. Its totient is φ = 27125280.

The previous prime is 28987373. The next prime is 28987411. The reversal of 28987391 is 19378982.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28987391 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28987991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 137276 + ... + 137486.

It is an arithmetic number, because the mean of its divisors is an integer number (1933440).

Almost surely, 2^28987391 is an apocalyptic number.

28987391 is a deficient number, since it is larger than the sum of its proper divisors (1947649).

28987391 is a wasteful number, since it uses less digits than its factorization.

28987391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 374.

The product of its digits is 217728, while the sum is 47.

The square root of 28987391 is about 5383.9939635925. The cubic root of 28987391 is about 307.1871487080.

The spelling of 28987391 in words is "twenty-eight million, nine hundred eighty-seven thousand, three hundred ninety-one".