66540013 has 2 divisors, whose sum is σ = 66540014. Its totient is φ = 66540012.

The previous prime is 66539969. The next prime is 66540017. The reversal of 66540013 is 31004566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66536649 + 3364 = 8157^2 + 58^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66540013 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66540013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66540017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33270006 + 33270007.

It is an arithmetic number, because the mean of its divisors is an integer number (33270007).

Almost surely, 2^66540013 is an apocalyptic number.

It is an amenable number.

66540013 is a deficient number, since it is larger than the sum of its proper divisors (1).

66540013 is an equidigital number, since it uses as much as digits as its factorization.

66540013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 66540013 is about 8157.2062006547. The cubic root of 66540013 is about 405.2231925291.

Adding to 66540013 its reverse (31004566), we get a palindrome (97544579).

The spelling of 66540013 in words is "sixty-six million, five hundred forty thousand, thirteen".