66511567691 has 2 divisors, whose sum is σ = 66511567692. Its totient is φ = 66511567690.

The previous prime is 66511567651. The next prime is 66511567699. The reversal of 66511567691 is 19676511566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66511567691 - 2⁶ = 66511567627 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (66511567699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33255783845 + 33255783846.

It is an arithmetic number, because the mean of its divisors is an integer number (33255783846).

Almost surely, 2^66511567691 is an apocalyptic number.

66511567691 is a deficient number, since it is larger than the sum of its proper divisors (1).

66511567691 is an equidigital number, since it uses as much as digits as its factorization.

66511567691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2041200, while the sum is 53.

The spelling of 66511567691 in words is "sixty-six billion, five hundred eleven million, five hundred sixty-seven thousand, six hundred ninety-one".