66678687749 has 2 divisors, whose sum is σ = 66678687750. Its totient is φ = 66678687748.

The previous prime is 66678687661. The next prime is 66678687769. The reversal of 66678687749 is 94778687666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66194027524 + 484660225 = 257282^2 + 22015^2 .

It is a cyclic number.

It is not a de Polignac number, because 66678687749 - 2³² = 62383720453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66678687769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33339343874 + 33339343875.

It is an arithmetic number, because the mean of its divisors is an integer number (33339343875).

Almost surely, 2^66678687749 is an apocalyptic number.

It is an amenable number.

66678687749 is a deficient number, since it is larger than the sum of its proper divisors (1).

66678687749 is an equidigital number, since it uses as much as digits as its factorization.

66678687749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1024192512, while the sum is 74.

The spelling of 66678687749 in words is "sixty-six billion, six hundred seventy-eight million, six hundred eighty-seven thousand, seven hundred forty-nine".