28921987 has 2 divisors, whose sum is σ = 28921988. Its totient is φ = 28921986.

The previous prime is 28921969. The next prime is 28921999. The reversal of 28921987 is 78912982.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28921987 - 2²³ = 20533379 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28921927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14460993 + 14460994.

It is an arithmetic number, because the mean of its divisors is an integer number (14460994).

Almost surely, 2^28921987 is an apocalyptic number.

28921987 is a deficient number, since it is larger than the sum of its proper divisors (1).

28921987 is an equidigital number, since it uses as much as digits as its factorization.

28921987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 46.

The square root of 28921987 is about 5377.9166040392. The cubic root of 28921987 is about 306.9559401591.

The spelling of 28921987 in words is "twenty-eight million, nine hundred twenty-one thousand, nine hundred eighty-seven".