221688668 has 6 divisors (see below), whose sum is σ = 387955176. Its totient is φ = 110844332.

The previous prime is 221688667. The next prime is 221688671. The reversal of 221688668 is 866886122.

It is a super-2 number, since 2×221688668² = 98291731039228448, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221688667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27711080 + ... + 27711087.

It is an arithmetic number, because the mean of its divisors is an integer number (64659196).

Almost surely, 2^221688668 is an apocalyptic number.

It is an amenable number.

221688668 is a deficient number, since it is larger than the sum of its proper divisors (166266508).

221688668 is a wasteful number, since it uses less digits than its factorization.

221688668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55422171 (or 55422169 counting only the distinct ones).

The product of its digits is 442368, while the sum is 47.

The square root of 221688668 is about 14889.2131424061. The cubic root of 221688668 is about 605.2217096032.

The spelling of 221688668 in words is "two hundred twenty-one million, six hundred eighty-eight thousand, six hundred sixty-eight".