66642617666 has 8 divisors (see below), whose sum is σ = 100042210620. Its totient is φ = 33295214128.

The previous prime is 66642617663. The next prime is 66642617731. The reversal of 66642617666 is 66671624666.

It can be written as a sum of positive squares in 2 ways, for example, as 60976894225 + 5665723441 = 246935^2 + 75271^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (66642617663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13044161 + ... + 13049268.

Almost surely, 2^66642617666 is an apocalyptic number.

66642617666 is a deficient number, since it is larger than the sum of its proper divisors (33399592954).

66642617666 is a wasteful number, since it uses less digits than its factorization.

66642617666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26094708.

The product of its digits is 15676416, while the sum is 56.

The spelling of 66642617666 in words is "sixty-six billion, six hundred forty-two million, six hundred seventeen thousand, six hundred sixty-six".