21845287 has 2 divisors, whose sum is σ = 21845288. Its totient is φ = 21845286.

The previous prime is 21845261. The next prime is 21845293. The reversal of 21845287 is 78254812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21845287 is a prime.

It is a super-2 number, since 2×21845287² = 954433128224738, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21845237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922643 + 10922644.

It is an arithmetic number, because the mean of its divisors is an integer number (10922644).

Almost surely, 2^21845287 is an apocalyptic number.

21845287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845287 is an equidigital number, since it uses as much as digits as its factorization.

21845287 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35840, while the sum is 37.

The square root of 21845287 is about 4673.8942007709. The cubic root of 21845287 is about 279.5455510793.

The spelling of 21845287 in words is "twenty-one million, eight hundred forty-five thousand, two hundred eighty-seven".