66605665601 has 2 divisors, whose sum is σ = 66605665602. Its totient is φ = 66605665600.

The previous prime is 66605665591. The next prime is 66605665619. The reversal of 66605665601 is 10656650666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52258417201 + 14347248400 = 228601^2 + 119780^2 .

It is a cyclic number.

It is not a de Polignac number, because 66605665601 - 2¹⁸ = 66605403457 is a prime.

It is not a weakly prime, because it can be changed into another prime (66605665501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33302832800 + 33302832801.

It is an arithmetic number, because the mean of its divisors is an integer number (33302832801).

Almost surely, 2^66605665601 is an apocalyptic number.

It is an amenable number.

66605665601 is a deficient number, since it is larger than the sum of its proper divisors (1).

66605665601 is an equidigital number, since it uses as much as digits as its factorization.

66605665601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1166400, while the sum is 47.

The spelling of 66605665601 in words is "sixty-six billion, six hundred five million, six hundred sixty-five thousand, six hundred one".