21910666 has 8 divisors (see below), whose sum is σ = 32943204. Its totient is φ = 10929600.

The previous prime is 21910663. The next prime is 21910673. The reversal of 21910666 is 66601912.

It can be written as a sum of positive squares in 2 ways, for example, as 21427641 + 483025 = 4629^2 + 695^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21910663) 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 3 ways as a sum of consecutive naturals, for example, 11785 + ... + 13516.

Almost surely, 2^21910666 is an apocalyptic number.

21910666 is a deficient number, since it is larger than the sum of its proper divisors (11032538).

21910666 is a wasteful number, since it uses less digits than its factorization.

21910666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25736.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 21910666 is about 4680.8830363512. The cubic root of 21910666 is about 279.8241497869.

The spelling of 21910666 in words is "twenty-one million, nine hundred ten thousand, six hundred sixty-six".