217821106 has 16 divisors (see below), whose sum is σ = 329769216. Its totient is φ = 107902656.

The previous prime is 217821067. The next prime is 217821137. The reversal of 217821106 is 601128712.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121690 + ... + 123466.

It is an arithmetic number, because the mean of its divisors is an integer number (20610576).

Almost surely, 2^217821106 is an apocalyptic number.

217821106 is a deficient number, since it is larger than the sum of its proper divisors (111948110).

217821106 is a wasteful number, since it uses less digits than its factorization.

217821106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2313.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 217821106 is about 14758.7637016113. The cubic root of 217821106 is about 601.6814924955.

Adding to 217821106 its reverse (601128712), we get a palindrome (818949818).

The spelling of 217821106 in words is "two hundred seventeen million, eight hundred twenty-one thousand, one hundred six".