66681607 has 2 divisors, whose sum is σ = 66681608. Its totient is φ = 66681606.

The previous prime is 66681547. The next prime is 66681613. The reversal of 66681607 is 70618666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66681607 - 2²³ = 58292999 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66681607.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66681647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340803 + 33340804.

It is an arithmetic number, because the mean of its divisors is an integer number (33340804).

Almost surely, 2^66681607 is an apocalyptic number.

66681607 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681607 is an equidigital number, since it uses as much as digits as its factorization.

66681607 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 66681607 is about 8165.8806628557. The cubic root of 66681607 is about 405.5104208175.

The spelling of 66681607 in words is "sixty-six million, six hundred eighty-one thousand, six hundred seven".