21031263 has 12 divisors (see below), whose sum is σ = 33140328. Its totient is φ = 12746160.

The previous prime is 21031253. The next prime is 21031277. The reversal of 21031263 is 36213012.

It is not a de Polignac number, because 21031263 - 2¹⁰ = 21030239 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031253) 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 in 11 ways as a sum of consecutive naturals, for example, 106120 + ... + 106317.

It is an arithmetic number, because the mean of its divisors is an integer number (2761694).

Almost surely, 2^21031263 is an apocalyptic number.

21031263 is a deficient number, since it is larger than the sum of its proper divisors (12109065).

21031263 is a wasteful number, since it uses less digits than its factorization.

21031263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212454 (or 212451 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21031263 is about 4585.9854993229. The cubic root of 21031263 is about 276.0292580829.

Adding to 21031263 its reverse (36213012), we get a palindrome (57244275).

The spelling of 21031263 in words is "twenty-one million, thirty-one thousand, two hundred sixty-three".