221994721 has 8 divisors (see below), whose sum is σ = 253134504. Its totient is φ = 192864000.

The previous prime is 221994713. The next prime is 221994733. The reversal of 221994721 is 127499122.

It can be written as a sum of positive squares in 4 ways, for example, as 89491600 + 132503121 = 9460^2 + 11511^2 .

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 221994721 - 2³ = 221994713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221994701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502030 + ... + 502471.

It is an arithmetic number, because the mean of its divisors is an integer number (31641813).

Almost surely, 2^221994721 is an apocalyptic number.

It is an amenable number.

221994721 is a deficient number, since it is larger than the sum of its proper divisors (31139783).

221994721 is a wasteful number, since it uses less digits than its factorization.

221994721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1004531.

The product of its digits is 18144, while the sum is 37.

The square root of 221994721 is about 14899.4872730574. The cubic root of 221994721 is about 605.5000951231.

The spelling of 221994721 in words is "two hundred twenty-one million, nine hundred ninety-four thousand, seven hundred twenty-one".