221128979 has 8 divisors (see below), whose sum is σ = 237101760. Its totient is φ = 205485696.

The previous prime is 221128933. The next prime is 221128997. The reversal of 221128979 is 979821122.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221128979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221128079) 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, 80984 + ... + 83669.

It is an arithmetic number, because the mean of its divisors is an integer number (29637720).

Almost surely, 2^221128979 is an apocalyptic number.

221128979 is a deficient number, since it is larger than the sum of its proper divisors (15972781).

221128979 is a wasteful number, since it uses less digits than its factorization.

221128979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164749.

The product of its digits is 36288, while the sum is 41.

The square root of 221128979 is about 14870.4061477822. The cubic root of 221128979 is about 604.7119535842.

The spelling of 221128979 in words is "two hundred twenty-one million, one hundred twenty-eight thousand, nine hundred seventy-nine".