191676721 has 2 divisors, whose sum is σ = 191676722. Its totient is φ = 191676720.

The previous prime is 191676707. The next prime is 191676739. The reversal of 191676721 is 127676191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 125888400 + 65788321 = 11220^2 + 8111^2 .

It is a cyclic number.

It is not a de Polignac number, because 191676721 - 2⁹ = 191676209 is a prime.

It is not a weakly prime, because it can be changed into another prime (191677721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95838360 + 95838361.

It is an arithmetic number, because the mean of its divisors is an integer number (95838361).

Almost surely, 2^191676721 is an apocalyptic number.

It is an amenable number.

191676721 is a deficient number, since it is larger than the sum of its proper divisors (1).

191676721 is an equidigital number, since it uses as much as digits as its factorization.

191676721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31752, while the sum is 40.

The square root of 191676721 is about 13844.7362199502. The cubic root of 191676721 is about 576.5758622026.

The spelling of 191676721 in words is "one hundred ninety-one million, six hundred seventy-six thousand, seven hundred twenty-one".