221381717 has 4 divisors (see below), whose sum is σ = 222137580. Its totient is φ = 220625856.

The previous prime is 221381707. The next prime is 221381731. The reversal of 221381717 is 717183122.

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

It can be written as a sum of positive squares in 2 ways, for example, as 126922756 + 94458961 = 11266^2 + 9719^2 .

It is a cyclic number.

It is not a de Polignac number, because 221381717 - 2⁶ = 221381653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221381707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 377492 + ... + 378077.

It is an arithmetic number, because the mean of its divisors is an integer number (55534395).

Almost surely, 2^221381717 is an apocalyptic number.

It is an amenable number.

221381717 is a deficient number, since it is larger than the sum of its proper divisors (755863).

221381717 is an equidigital number, since it uses as much as digits as its factorization.

221381717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755862.

The product of its digits is 4704, while the sum is 32.

The square root of 221381717 is about 14878.9017403839. The cubic root of 221381717 is about 604.9422497981.

The spelling of 221381717 in words is "two hundred twenty-one million, three hundred eighty-one thousand, seven hundred seventeen".