21201287 has 2 divisors, whose sum is σ = 21201288. Its totient is φ = 21201286.

The previous prime is 21201281. The next prime is 21201289. The reversal of 21201287 is 78210212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21201287 - 2⁸ = 21201031 is a prime.

Together with 21201289, 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 (21201281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600643 + 10600644.

It is an arithmetic number, because the mean of its divisors is an integer number (10600644).

Almost surely, 2^21201287 is an apocalyptic number.

21201287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201287 is an equidigital number, since it uses as much as digits as its factorization.

21201287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21201287 is about 4604.4855304366. The cubic root of 21201287 is about 276.7711012005.

Adding to 21201287 its reverse (78210212), we get a palindrome (99411499).

The spelling of 21201287 in words is "twenty-one million, two hundred one thousand, two hundred eighty-seven".