66557918 has 16 divisors (see below), whose sum is σ = 114616320. Its totient is φ = 28395576.

The previous prime is 66557917. The next prime is 66557927. The reversal of 66557918 is 81975566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66557917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7538 + ... + 13781.

It is an arithmetic number, because the mean of its divisors is an integer number (7163520).

Almost surely, 2^66557918 is an apocalyptic number.

66557918 is a deficient number, since it is larger than the sum of its proper divisors (48058402).

66557918 is a wasteful number, since it uses less digits than its factorization.

66557918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21551.

The product of its digits is 453600, while the sum is 47.

The square root of 66557918 is about 8158.3036226902. The cubic root of 66557918 is about 405.2595359274.

The spelling of 66557918 in words is "sixty-six million, five hundred fifty-seven thousand, nine hundred eighteen".