21300287 has 2 divisors, whose sum is σ = 21300288. Its totient is φ = 21300286.

The previous prime is 21300233. The next prime is 21300289. The reversal of 21300287 is 78200312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21300287 is a prime.

Together with 21300289, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21300289) 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, 10650143 + 10650144.

It is an arithmetic number, because the mean of its divisors is an integer number (10650144).

Almost surely, 2^21300287 is an apocalyptic number.

21300287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21300287 is an equidigital number, since it uses as much as digits as its factorization.

21300287 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21300287 is about 4615.2233965432. The cubic root of 21300287 is about 277.2012291833.

Adding to 21300287 its reverse (78200312), we get a palindrome (99500599).

The spelling of 21300287 in words is "twenty-one million, three hundred thousand, two hundred eighty-seven".