221478666 has 16 divisors (see below), whose sum is σ = 445932000. Its totient is φ = 73330448.

The previous prime is 221478637. The next prime is 221478667. The reversal of 221478666 is 666874122.

It is not an unprimeable number, because it can be changed into a prime (221478667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 122976 + ... + 124763.

It is an arithmetic number, because the mean of its divisors is an integer number (27870750).

Almost surely, 2^221478666 is an apocalyptic number.

221478666 is an abundant number, since it is smaller than the sum of its proper divisors (224453334).

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

221478666 is a wasteful number, since it uses less digits than its factorization.

221478666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247893.

The product of its digits is 193536, while the sum is 42.

The square root of 221478666 is about 14882.1593191311. The cubic root of 221478666 is about 605.0305437304.

The spelling of 221478666 in words is "two hundred twenty-one million, four hundred seventy-eight thousand, six hundred sixty-six".