20928287 has 2 divisors, whose sum is σ = 20928288. Its totient is φ = 20928286.

The previous prime is 20928283. The next prime is 20928289. The reversal of 20928287 is 78282902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20928287 - 2² = 20928283 is a prime.

Together with 20928289, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20928287.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20928283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10464143 + 10464144.

It is an arithmetic number, because the mean of its divisors is an integer number (10464144).

Almost surely, 2^20928287 is an apocalyptic number.

20928287 is a deficient number, since it is larger than the sum of its proper divisors (1).

20928287 is an equidigital number, since it uses as much as digits as its factorization.

20928287 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20928287 is about 4574.7444737384. The cubic root of 20928287 is about 275.5780106992.

The spelling of 20928287 in words is "twenty million, nine hundred twenty-eight thousand, two hundred eighty-seven".