21665626 has 16 divisors (see below), whose sum is σ = 33436800. Its totient is φ = 10524448.

The previous prime is 21665587. The next prime is 21665641. The reversal of 21665626 is 62656612.

It is a junction number, because it is equal to n+sod(n) for n = 21665591 and 21665600.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 9471 + ... + 11533.

It is an arithmetic number, because the mean of its divisors is an integer number (2089800).

Almost surely, 2^21665626 is an apocalyptic number.

21665626 is a deficient number, since it is larger than the sum of its proper divisors (11771174).

21665626 is a wasteful number, since it uses less digits than its factorization.

21665626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2213.

The product of its digits is 25920, while the sum is 34.

The square root of 21665626 is about 4654.6348943822. The cubic root of 21665626 is about 278.7770901434. Note that the first 3 decimals are identical.

The spelling of 21665626 in words is "twenty-one million, six hundred sixty-five thousand, six hundred twenty-six".