21002287 has 2 divisors, whose sum is σ = 21002288. Its totient is φ = 21002286.

The previous prime is 21002269. The next prime is 21002299. The reversal of 21002287 is 78220012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002287 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002207) 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, 10501143 + 10501144.

It is an arithmetic number, because the mean of its divisors is an integer number (10501144).

Almost surely, 2^21002287 is an apocalyptic number.

21002287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002287 is an equidigital number, since it uses as much as digits as its factorization.

21002287 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 21002287 is about 4582.8252203199. The cubic root of 21002287 is about 275.9024326072.

Adding to 21002287 its reverse (78220012), we get a palindrome (99222299).

The spelling of 21002287 in words is "twenty-one million, two thousand, two hundred eighty-seven".