66647866 has 4 divisors (see below), whose sum is σ = 99971802. Its totient is φ = 33323932.

The previous prime is 66647857. The next prime is 66647869. The reversal of 66647866 is 66874666.

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., 65950641 + 697225 = 8121^2 + 835^2 .

It is not an unprimeable number, because it can be changed into a prime (66647869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16661965 + ... + 16661968.

Almost surely, 2^66647866 is an apocalyptic number.

66647866 is a deficient number, since it is larger than the sum of its proper divisors (33323936).

66647866 is a wasteful number, since it uses less digits than its factorization.

66647866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33323935.

The product of its digits is 1741824, while the sum is 49.

The square root of 66647866 is about 8163.8144270923. The cubic root of 66647866 is about 405.4420129705.

The spelling of 66647866 in words is "sixty-six million, six hundred forty-seven thousand, eight hundred sixty-six".