6661691 has 2 divisors, whose sum is σ = 6661692. Its totient is φ = 6661690.

The previous prime is 6661687. The next prime is 6661693. The reversal of 6661691 is 1961666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6661691 - 2² = 6661687 is a prime.

Together with 6661693, 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 (6661693) 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, 3330845 + 3330846.

It is an arithmetic number, because the mean of its divisors is an integer number (3330846).

Almost surely, 2^6661691 is an apocalyptic number.

6661691 is a deficient number, since it is larger than the sum of its proper divisors (1).

6661691 is an equidigital number, since it uses as much as digits as its factorization.

6661691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 35.

The square root of 6661691 is about 2581.0251839143. The cubic root of 6661691 is about 188.1603713066.

The spelling of 6661691 in words is "six million, six hundred sixty-one thousand, six hundred ninety-one".