21829666 has 8 divisors (see below), whose sum is σ = 34670700. Its totient is φ = 10272768.

The previous prime is 21829657. The next prime is 21829669. The reversal of 21829666 is 66692812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21298225 + 531441 = 4615^2 + 729^2 .

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 (21829669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 320991 + ... + 321058.

Almost surely, 2^21829666 is an apocalyptic number.

21829666 is a deficient number, since it is larger than the sum of its proper divisors (12841034).

21829666 is a wasteful number, since it uses less digits than its factorization.

21829666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642068.

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

The square root of 21829666 is about 4672.2228114678. Note that the first 3 decimals coincide. The cubic root of 21829666 is about 279.4789032584.

The spelling of 21829666 in words is "twenty-one million, eight hundred twenty-nine thousand, six hundred sixty-six".