66666749 has 2 divisors, whose sum is σ = 66666750. Its totient is φ = 66666748.

The previous prime is 66666731. The next prime is 66666751. The reversal of 66666749 is 94766666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 33431524 + 33235225 = 5782^2 + 5765^2 .

It is a cyclic number.

It is not a de Polignac number, because 66666749 - 2⁸ = 66666493 is a prime.

Together with 66666751, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 66666697 and 66666706.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66666049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33333374 + 33333375.

It is an arithmetic number, because the mean of its divisors is an integer number (33333375).

Almost surely, 2^66666749 is an apocalyptic number.

It is an amenable number.

66666749 is a deficient number, since it is larger than the sum of its proper divisors (1).

66666749 is an equidigital number, since it uses as much as digits as its factorization.

66666749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 50.

The square root of 66666749 is about 8164.9708511421. The cubic root of 66666749 is about 405.4802999608.

The spelling of 66666749 in words is "sixty-six million, six hundred sixty-six thousand, seven hundred forty-nine".