221138191 has 4 divisors (see below), whose sum is σ = 221184432. Its totient is φ = 221091952.

The previous prime is 221138171. The next prime is 221138209. The reversal of 221138191 is 191831122.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221138191 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 (221138171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14995 + ... + 25828.

It is an arithmetic number, because the mean of its divisors is an integer number (55296108).

Almost surely, 2^221138191 is an apocalyptic number.

221138191 is a deficient number, since it is larger than the sum of its proper divisors (46241).

221138191 is an equidigital number, since it uses as much as digits as its factorization.

221138191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46240.

The product of its digits is 864, while the sum is 28.

The square root of 221138191 is about 14870.7158872732. The cubic root of 221138191 is about 604.7203506883.

The spelling of 221138191 in words is "two hundred twenty-one million, one hundred thirty-eight thousand, one hundred ninety-one".