221644666 has 4 divisors (see below), whose sum is σ = 332467002. Its totient is φ = 110822332.

The previous prime is 221644663. The next prime is 221644669. The reversal of 221644666 is 666446122.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (221644663) and next prime (221644669).

It can be written as a sum of positive squares in only one way, i.e., 117094041 + 104550625 = 10821^2 + 10225^2 .

It is not an unprimeable number, because it can be changed into a prime (221644663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55411165 + ... + 55411168.

Almost surely, 2^221644666 is an apocalyptic number.

221644666 is a deficient number, since it is larger than the sum of its proper divisors (110822336).

221644666 is a wasteful number, since it uses less digits than its factorization.

221644666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110822335.

The product of its digits is 82944, while the sum is 37.

The square root of 221644666 is about 14887.7354221520. The cubic root of 221644666 is about 605.1816643631.

The spelling of 221644666 in words is "two hundred twenty-one million, six hundred forty-four thousand, six hundred sixty-six".