66646666 has 4 divisors (see below), whose sum is σ = 99970002. Its totient is φ = 33323332.

The previous prime is 66646651. The next prime is 66646667. The reversal of 66646666 is 66664666.

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., 47541025 + 19105641 = 6895^2 + 4371^2 .

66646666 is a modest number, since divided by 6666 gives 6664 as remainder.

It is not an unprimeable number, because it can be changed into a prime (66646667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16661665 + ... + 16661668.

Almost surely, 2^66646666 is an apocalyptic number.

66646666 is a deficient number, since it is larger than the sum of its proper divisors (33323336).

66646666 is a wasteful number, since it uses less digits than its factorization.

66646666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33323335.

The product of its digits is 1119744, while the sum is 46.

The square root of 66646666 is about 8163.7409317053. The cubic root of 66646666 is about 405.4395796176.

The spelling of 66646666 in words is "sixty-six million, six hundred forty-six thousand, six hundred sixty-six".