221213866 has 16 divisors (see below), whose sum is σ = 339526656. Its totient is φ = 108047376.

The previous prime is 221213831. The next prime is 221213873. The reversal of 221213866 is 668312122.

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, 55120 + ... + 58996.

It is an arithmetic number, because the mean of its divisors is an integer number (21220416).

Almost surely, 2^221213866 is an apocalyptic number.

221213866 is a deficient number, since it is larger than the sum of its proper divisors (118312790).

221213866 is a wasteful number, since it uses less digits than its factorization.

221213866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4533.

The product of its digits is 6912, while the sum is 31.

The square root of 221213866 is about 14873.2600999243. The cubic root of 221213866 is about 604.7893226334.

Adding to 221213866 its reverse (668312122), we get a palindrome (889525988).

The spelling of 221213866 in words is "two hundred twenty-one million, two hundred thirteen thousand, eight hundred sixty-six".