221215668 has 12 divisors (see below), whose sum is σ = 516169920. Its totient is φ = 73738552.

The previous prime is 221215663. The next prime is 221215697. The reversal of 221215668 is 866512122.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221215661) 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, 9217308 + ... + 9217331.

It is an arithmetic number, because the mean of its divisors is an integer number (43014160).

Almost surely, 2^221215668 is an apocalyptic number.

It is an amenable number.

221215668 is an abundant number, since it is smaller than the sum of its proper divisors (294954252).

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

221215668 is a wasteful number, since it uses less digits than its factorization.

221215668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18434646 (or 18434644 counting only the distinct ones).

The product of its digits is 11520, while the sum is 33.

The square root of 221215668 is about 14873.3206783152. The cubic root of 221215668 is about 604.7909648261.

The spelling of 221215668 in words is "two hundred twenty-one million, two hundred fifteen thousand, six hundred sixty-eight".