21021263 has 2 divisors, whose sum is σ = 21021264. Its totient is φ = 21021262.

The previous prime is 21021251. The next prime is 21021293. The reversal of 21021263 is 36212012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21021263 - 2¹⁰ = 21020239 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510631 + 10510632.

It is an arithmetic number, because the mean of its divisors is an integer number (10510632).

Almost surely, 2^21021263 is an apocalyptic number.

21021263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021263 is an equidigital number, since it uses as much as digits as its factorization.

21021263 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21021263 is about 4584.8950914934. The cubic root of 21021263 is about 275.9855021090.

Adding to 21021263 its reverse (36212012), we get a palindrome (57233275).

The spelling of 21021263 in words is "twenty-one million, twenty-one thousand, two hundred sixty-three".