21663263 has 8 divisors (see below), whose sum is σ = 22659936. Its totient is φ = 20671200.

The previous prime is 21663251. The next prime is 21663277. The reversal of 21663263 is 36236612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21663263 - 2⁴ = 21663247 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 (21663283) 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 7 ways as a sum of consecutive naturals, for example, 11573 + ... + 13313.

It is an arithmetic number, because the mean of its divisors is an integer number (2832492).

Almost surely, 2^21663263 is an apocalyptic number.

21663263 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21663263 is a deficient number, since it is larger than the sum of its proper divisors (996673).

21663263 is a wasteful number, since it uses less digits than its factorization.

21663263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2305.

The product of its digits is 7776, while the sum is 29.

The square root of 21663263 is about 4654.3810544475. The cubic root of 21663263 is about 278.7669546686.

Adding to 21663263 its reverse (36236612), we get a palindrome (57899875).

The spelling of 21663263 in words is "twenty-one million, six hundred sixty-three thousand, two hundred sixty-three".