21663633 has 8 divisors (see below), whose sum is σ = 28907200. Its totient is φ = 14431248.

The previous prime is 21663623. The next prime is 21663647. The reversal of 21663633 is 33636612.

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

It is not a de Polignac number, because 21663633 - 2¹⁰ = 21662609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21663633.

It is not an unprimeable number, because it can be changed into a prime (21663623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4308 + ... + 7866.

It is an arithmetic number, because the mean of its divisors is an integer number (3613400).

Almost surely, 2^21663633 is an apocalyptic number.

It is an amenable number.

21663633 is a deficient number, since it is larger than the sum of its proper divisors (7243567).

21663633 is a wasteful number, since it uses less digits than its factorization.

21663633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5591.

The product of its digits is 11664, while the sum is 30.

The square root of 21663633 is about 4654.4208017754. The cubic root of 21663633 is about 278.7685417362.

The spelling of 21663633 in words is "twenty-one million, six hundred sixty-three thousand, six hundred thirty-three".