66740813 has 2 divisors, whose sum is σ = 66740814. Its totient is φ = 66740812.

The previous prime is 66740801. The next prime is 66740831. The reversal of 66740813 is 31804766.

Together with next prime (66740831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42159049 + 24581764 = 6493^2 + 4958^2 .

It is a cyclic number.

It is not a de Polignac number, because 66740813 - 2⁴ = 66740797 is a prime.

It is a super-2 number, since 2×66740813² = 8908672239801938, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66740873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33370406 + 33370407.

It is an arithmetic number, because the mean of its divisors is an integer number (33370407).

Almost surely, 2^66740813 is an apocalyptic number.

It is an amenable number.

66740813 is a deficient number, since it is larger than the sum of its proper divisors (1).

66740813 is an equidigital number, since it uses as much as digits as its factorization.

66740813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24192, while the sum is 35.

The square root of 66740813 is about 8169.5050645679. The cubic root of 66740813 is about 405.6304016682.

The spelling of 66740813 in words is "sixty-six million, seven hundred forty thousand, eight hundred thirteen".