21664433 has 8 divisors (see below), whose sum is σ = 24897600. Its totient is φ = 18465840.

The previous prime is 21664417. The next prime is 21664457. The reversal of 21664433 is 33446612.

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 21664433 - 2⁴ = 21664417 is a prime.

It is a super-2 number, since 2×21664433² = 938695314422978, which contains 22 as substring.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21664396 and 21664405.

It is not an unprimeable number, because it can be changed into a prime (21664483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7283 + ... + 9816.

It is an arithmetic number, because the mean of its divisors is an integer number (3112200).

Almost surely, 2^21664433 is an apocalyptic number.

It is an amenable number.

21664433 is a deficient number, since it is larger than the sum of its proper divisors (3233167).

21664433 is a wasteful number, since it uses less digits than its factorization.

21664433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17287.

The product of its digits is 10368, while the sum is 29.

The square root of 21664433 is about 4654.5067407836. The cubic root of 21664433 is about 278.7719731718.

The spelling of 21664433 in words is "twenty-one million, six hundred sixty-four thousand, four hundred thirty-three".