66649718 has 4 divisors (see below), whose sum is σ = 99974580. Its totient is φ = 33324858.

The previous prime is 66649717. The next prime is 66649729. The reversal of 66649718 is 81794666.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66649711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16662428 + ... + 16662431.

It is an arithmetic number, because the mean of its divisors is an integer number (24993645).

Almost surely, 2^66649718 is an apocalyptic number.

66649718 is a deficient number, since it is larger than the sum of its proper divisors (33324862).

66649718 is a wasteful number, since it uses less digits than its factorization.

66649718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33324861.

The product of its digits is 435456, while the sum is 47.

The square root of 66649718 is about 8163.9278536744. The cubic root of 66649718 is about 405.4457683878.

The spelling of 66649718 in words is "sixty-six million, six hundred forty-nine thousand, seven hundred eighteen".