21217106 has 16 divisors (see below), whose sum is σ = 32319000. Its totient is φ = 10445568.

The previous prime is 21217087. The next prime is 21217111. The reversal of 21217106 is 60171212.

It can be written as a sum of positive squares in 4 ways, for example, as 9030025 + 12187081 = 3005^2 + 3491^2 .

It is a Curzon 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, 60620 + ... + 60968.

Almost surely, 2^21217106 is an apocalyptic number.

21217106 is a deficient number, since it is larger than the sum of its proper divisors (11101894).

21217106 is a wasteful number, since it uses less digits than its factorization.

21217106 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 21217106 is about 4606.2029916190. The cubic root of 21217106 is about 276.8399201922.

Adding to 21217106 its reverse (60171212), we get a palindrome (81388318).

The spelling of 21217106 in words is "twenty-one million, two hundred seventeen thousand, one hundred six".