21263863 has 4 divisors (see below), whose sum is σ = 21838600. Its totient is φ = 20689128.

The previous prime is 21263819. The next prime is 21263867. The reversal of 21263863 is 36836212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21263863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21263867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 287313 + ... + 287386.

It is an arithmetic number, because the mean of its divisors is an integer number (5459650).

Almost surely, 2^21263863 is an apocalyptic number.

21263863 is a deficient number, since it is larger than the sum of its proper divisors (574737).

21263863 is an equidigital number, since it uses as much as digits as its factorization.

21263863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574736.

The product of its digits is 10368, while the sum is 31.

The square root of 21263863 is about 4611.2756369577. The cubic root of 21263863 is about 277.0431321228.

The spelling of 21263863 in words is "twenty-one million, two hundred sixty-three thousand, eight hundred sixty-three".