21298666 has 8 divisors (see below), whose sum is σ = 31977540. Its totient is φ = 10639488.

The previous prime is 21298583. The next prime is 21298681. The reversal of 21298666 is 66689212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21298225 + 441 = 4615^2 + 21^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1831 + ... + 6778.

Almost surely, 2^21298666 is an apocalyptic number.

21298666 is a deficient number, since it is larger than the sum of its proper divisors (10678874).

21298666 is a wasteful number, since it uses less digits than its factorization.

21298666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9848.

The product of its digits is 62208, while the sum is 40.

The square root of 21298666 is about 4615.0477787343. The cubic root of 21298666 is about 277.1941971248.

The spelling of 21298666 in words is "twenty-one million, two hundred ninety-eight thousand, six hundred sixty-six".