221979217 has 8 divisors (see below), whose sum is σ = 235440000. Its totient is φ = 208563264.

The previous prime is 221979209. The next prime is 221979221. The reversal of 221979217 is 712979122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221979217 - 2³ = 221979209 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221979217.

It is not an unprimeable number, because it can be changed into a prime (221979227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 717 + ... + 21082.

It is an arithmetic number, because the mean of its divisors is an integer number (29430000).

Almost surely, 2^221979217 is an apocalyptic number.

It is an amenable number.

221979217 is a deficient number, since it is larger than the sum of its proper divisors (13460783).

221979217 is a wasteful number, since it uses less digits than its factorization.

221979217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22415.

The product of its digits is 31752, while the sum is 40.

The square root of 221979217 is about 14898.9669776129. The cubic root of 221979217 is about 605.4859988539.

The spelling of 221979217 in words is "two hundred twenty-one million, nine hundred seventy-nine thousand, two hundred seventeen".