66661606515 has 16 divisors (see below), whose sum is σ = 121895509248. Its totient is φ = 30473877216.

The previous prime is 66661606513. The next prime is 66661606519. The reversal of 66661606515 is 51560616666.

It is not a de Polignac number, because 66661606515 - 2¹ = 66661606513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66661606513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 317436117 + ... + 317436326.

It is an arithmetic number, because the mean of its divisors is an integer number (7618469328).

Almost surely, 2^66661606515 is an apocalyptic number.

66661606515 is a deficient number, since it is larger than the sum of its proper divisors (55233902733).

66661606515 is a wasteful number, since it uses less digits than its factorization.

66661606515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634872458.

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 66661606515 in words is "sixty-six billion, six hundred sixty-one million, six hundred six thousand, five hundred fifteen".