66689839 has 2 divisors, whose sum is σ = 66689840. Its totient is φ = 66689838.

The previous prime is 66689813. The next prime is 66689849. The reversal of 66689839 is 93898666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66689839 - 2⁹ = 66689327 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66689839.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66689849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33344919 + 33344920.

It is an arithmetic number, because the mean of its divisors is an integer number (33344920).

Almost surely, 2^66689839 is an apocalyptic number.

66689839 is a deficient number, since it is larger than the sum of its proper divisors (1).

66689839 is an equidigital number, since it uses as much as digits as its factorization.

66689839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3359232, while the sum is 55.

The square root of 66689839 is about 8166.3846958125. The cubic root of 66689839 is about 405.5271072002.

It can be divided in two parts, 66689 and 839, that added together give a triangular number (67528 = T₃₆₇).

The spelling of 66689839 in words is "sixty-six million, six hundred eighty-nine thousand, eight hundred thirty-nine".