28987531 has 2 divisors, whose sum is σ = 28987532. Its totient is φ = 28987530.

The previous prime is 28987529. The next prime is 28987537. The reversal of 28987531 is 13578982.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28987531 - 2¹ = 28987529 is a prime.

It is a super-2 number, since 2×28987531² = 1680553906951922, which contains 22 as substring.

Together with 28987529, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28987537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14493765 + 14493766.

It is an arithmetic number, because the mean of its divisors is an integer number (14493766).

Almost surely, 2^28987531 is an apocalyptic number.

28987531 is a deficient number, since it is larger than the sum of its proper divisors (1).

28987531 is an equidigital number, since it uses as much as digits as its factorization.

28987531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 43.

The square root of 28987531 is about 5384.0069650772. The cubic root of 28987531 is about 307.1876432464.

The spelling of 28987531 in words is "twenty-eight million, nine hundred eighty-seven thousand, five hundred thirty-one".