21633009 has 16 divisors (see below), whose sum is σ = 29898240. Its totient is φ = 13898880.

The previous prime is 21632983. The next prime is 21633011. The reversal of 21633009 is 90033612.

It is not a de Polignac number, because 21633009 - 2⁹ = 21632497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21633009.

It is not an unprimeable number, because it can be changed into a prime (21637009) 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 15 ways as a sum of consecutive naturals, for example, 42247 + ... + 42755.

It is an arithmetic number, because the mean of its divisors is an integer number (1868640).

Almost surely, 2^21633009 is an apocalyptic number.

It is an amenable number.

21633009 is a deficient number, since it is larger than the sum of its proper divisors (8265231).

21633009 is a wasteful number, since it uses less digits than its factorization.

21633009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000.

The product of its (nonzero) digits is 972, while the sum is 24.

The square root of 21633009 is about 4651.1298627323. The cubic root of 21633009 is about 278.6371228177.

The spelling of 21633009 in words is "twenty-one million, six hundred thirty-three thousand, nine".