21053287 has 2 divisors, whose sum is σ = 21053288. Its totient is φ = 21053286.

The previous prime is 21053281. The next prime is 21053297. The reversal of 21053287 is 78235012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21053287 - 2¹⁹ = 20528999 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 (21053281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526643 + 10526644.

It is an arithmetic number, because the mean of its divisors is an integer number (10526644).

Almost surely, 2^21053287 is an apocalyptic number.

21053287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053287 is an equidigital number, since it uses as much as digits as its factorization.

21053287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 21053287 is about 4588.3860997087. The cubic root of 21053287 is about 276.1255773504.

Adding to 21053287 its reverse (78235012), we get a palindrome (99288299).

The spelling of 21053287 in words is "twenty-one million, fifty-three thousand, two hundred eighty-seven".