66681739 has 2 divisors, whose sum is σ = 66681740. Its totient is φ = 66681738.

The previous prime is 66681677. The next prime is 66681749. The reversal of 66681739 is 93718666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66681739 - 2¹³ = 66673547 is a prime.

It is not a weakly prime, because it can be changed into another prime (66681749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340869 + 33340870.

It is an arithmetic number, because the mean of its divisors is an integer number (33340870).

Almost surely, 2^66681739 is an apocalyptic number.

66681739 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681739 is an equidigital number, since it uses as much as digits as its factorization.

66681739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 46.

The square root of 66681739 is about 8165.8887452622. Note that the first 3 decimals coincide. The cubic root of 66681739 is about 405.5106883943.

The spelling of 66681739 in words is "sixty-six million, six hundred eighty-one thousand, seven hundred thirty-nine".