21260287 has 2 divisors, whose sum is σ = 21260288. Its totient is φ = 21260286.

The previous prime is 21260279. The next prime is 21260293. The reversal of 21260287 is 78206212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21260287 - 2³ = 21260279 is a prime.

It is a Chen prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21260207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630143 + 10630144.

It is an arithmetic number, because the mean of its divisors is an integer number (10630144).

Almost surely, 2^21260287 is an apocalyptic number.

21260287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21260287 is an equidigital number, since it uses as much as digits as its factorization.

21260287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21260287 is about 4610.8878754531. The cubic root of 21260287 is about 277.0276008937.

Adding to 21260287 its reverse (78206212), we get a palindrome (99466499).

The spelling of 21260287 in words is "twenty-one million, two hundred sixty thousand, two hundred eighty-seven".