66808501809949 has 2 divisors, whose sum is σ = 66808501809950. Its totient is φ = 66808501809948.

The previous prime is 66808501809937. The next prime is 66808501809997. The reversal of 66808501809949 is 94990810580866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37778011689924 + 29030490120025 = 6146382^2 + 5387995^2 .

It is a cyclic number.

It is not a de Polignac number, because 66808501809949 - 2²¹ = 66808499712797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66808501809349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33404250904974 + 33404250904975.

It is an arithmetic number, because the mean of its divisors is an integer number (33404250904975).

Almost surely, 2^{66808501809949} is an apocalyptic number.

It is an amenable number.

66808501809949 is a deficient number, since it is larger than the sum of its proper divisors (1).

66808501809949 is an equidigital number, since it uses as much as digits as its factorization.

66808501809949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 268738560, while the sum is 73.

The spelling of 66808501809949 in words is "sixty-six trillion, eight hundred eight billion, five hundred one million, eight hundred nine thousand, nine hundred forty-nine".