221378191 has 4 divisors (see below), whose sum is σ = 225555192. Its totient is φ = 217201192.

The previous prime is 221378173. The next prime is 221378221. The reversal of 221378191 is 191873122.

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

It is a cyclic number.

It is not a de Polignac number, because 221378191 - 2⁹ = 221377679 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 (221375191) 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 3 ways as a sum of consecutive naturals, for example, 2088421 + ... + 2088526.

It is an arithmetic number, because the mean of its divisors is an integer number (56388798).

Almost surely, 2^221378191 is an apocalyptic number.

221378191 is a deficient number, since it is larger than the sum of its proper divisors (4177001).

221378191 is an equidigital number, since it uses as much as digits as its factorization.

221378191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4177000.

The product of its digits is 6048, while the sum is 34.

The square root of 221378191 is about 14878.7832499839. The cubic root of 221378191 is about 604.9390380940.

The spelling of 221378191 in words is "two hundred twenty-one million, three hundred seventy-eight thousand, one hundred ninety-one".