66621670666 has 4 divisors (see below), whose sum is σ = 99932506002. Its totient is φ = 33310835332.

The previous prime is 66621670657. The next prime is 66621670693. The reversal of 66621670666 is 66607612666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 63330239025 + 3291431641 = 251655^2 + 57371^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16655417665 + ... + 16655417668.

Almost surely, 2^66621670666 is an apocalyptic number.

66621670666 is a deficient number, since it is larger than the sum of its proper divisors (33310835336).

66621670666 is a wasteful number, since it uses less digits than its factorization.

66621670666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33310835335.

The product of its (nonzero) digits is 3919104, while the sum is 52.

The spelling of 66621670666 in words is "sixty-six billion, six hundred twenty-one million, six hundred seventy thousand, six hundred sixty-six".