21233663 has 16 divisors (see below), whose sum is σ = 24675840. Its totient is φ = 18057600.

The previous prime is 21233651. The next prime is 21233689. The reversal of 21233663 is 36633212.

It is a Cunningham number, because it is equal to 4608²-1.

It is not a de Polignac number, because 21233663 - 2⁴ = 21233647 is a prime.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21233603) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50468 + ... + 50886.

It is an arithmetic number, because the mean of its divisors is an integer number (1542240).

Almost surely, 2^21233663 is an apocalyptic number.

21233663 is a deficient number, since it is larger than the sum of its proper divisors (3442177).

21233663 is a wasteful number, since it uses less digits than its factorization.

21233663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718.

The product of its digits is 3888, while the sum is 26.

The square root of 21233663 is about 4607.9998914931. Note that the first 3 decimals coincide. The cubic root of 21233663 is about 276.9119131520.

Adding to 21233663 its reverse (36633212), we get a palindrome (57866875).

The spelling of 21233663 in words is "twenty-one million, two hundred thirty-three thousand, six hundred sixty-three".