21666326 has 16 divisors (see below), whose sum is σ = 35985600. Its totient is φ = 9700680.

The previous prime is 21666317. The next prime is 21666329. The reversal of 21666326 is 62366612.

It is a junction number, because it is equal to n+sod(n) for n = 21666292 and 21666301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666329) 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, 5876 + ... + 8823.

It is an arithmetic number, because the mean of its divisors is an integer number (2249100).

Almost surely, 2^21666326 is an apocalyptic number.

21666326 is a deficient number, since it is larger than the sum of its proper divisors (14319274).

21666326 is a wasteful number, since it uses less digits than its factorization.

21666326 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14779.

The product of its digits is 15552, while the sum is 32.

The square root of 21666326 is about 4654.7100876424. The cubic root of 21666326 is about 278.7800924700.

The spelling of 21666326 in words is "twenty-one million, six hundred sixty-six thousand, three hundred twenty-six".