21368287 has 2 divisors, whose sum is σ = 21368288. Its totient is φ = 21368286.

The previous prime is 21368261. The next prime is 21368297. The reversal of 21368287 is 78286312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21368287 - 2¹¹ = 21366239 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21368297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684143 + 10684144.

It is an arithmetic number, because the mean of its divisors is an integer number (10684144).

Almost surely, 2^21368287 is an apocalyptic number.

21368287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368287 is an equidigital number, since it uses as much as digits as its factorization.

21368287 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256, while the sum is 37.

The square root of 21368287 is about 4622.5844502832. The cubic root of 21368287 is about 277.4958990818.

The spelling of 21368287 in words is "twenty-one million, three hundred sixty-eight thousand, two hundred eighty-seven".