21708066 has 16 divisors (see below), whose sum is σ = 44913600. Its totient is φ = 6986448.

The previous prime is 21708059. The next prime is 21708097. The reversal of 21708066 is 66080712.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62206 + ... + 62553.

It is an arithmetic number, because the mean of its divisors is an integer number (2807100).

Almost surely, 2^21708066 is an apocalyptic number.

21708066 is an abundant number, since it is smaller than the sum of its proper divisors (23205534).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21708066 is a wasteful number, since it uses less digits than its factorization.

21708066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124793.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 21708066 is about 4659.1915607753. The cubic root of 21708066 is about 278.9590001545.

Adding to 21708066 its reverse (66080712), we get a palindrome (87788778).

The spelling of 21708066 in words is "twenty-one million, seven hundred eight thousand, sixty-six".