221187689 has 2 divisors, whose sum is σ = 221187690. Its totient is φ = 221187688.

The previous prime is 221187643. The next prime is 221187691. The reversal of 221187689 is 986781122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 221027689 + 160000 = 14867^2 + 400^2 .

It is a cyclic number.

It is not a de Polignac number, because 221187689 - 2⁸ = 221187433 is a prime.

Together with 221187691, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221181689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110593844 + 110593845.

It is an arithmetic number, because the mean of its divisors is an integer number (110593845).

Almost surely, 2^221187689 is an apocalyptic number.

It is an amenable number.

221187689 is a deficient number, since it is larger than the sum of its proper divisors (1).

221187689 is an equidigital number, since it uses as much as digits as its factorization.

221187689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96768, while the sum is 44.

The square root of 221187689 is about 14872.3800717975. The cubic root of 221187689 is about 604.7654660900.

The spelling of 221187689 in words is "two hundred twenty-one million, one hundred eighty-seven thousand, six hundred eighty-nine".