66555566 has 48 divisors (see below), whose sum is σ = 126977760. Its totient is φ = 25608000.

The previous prime is 66555553. The next prime is 66555581.

66555566 is nontrivially palindromic in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 170900 + ... + 171288.

It is an arithmetic number, because the mean of its divisors is an integer number (2645370).

Almost surely, 2^66555566 is an apocalyptic number.

66555566 is a deficient number, since it is larger than the sum of its proper divisors (60422194).

66555566 is a wasteful number, since it uses less digits than its factorization.

66555566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521 (or 510 counting only the distinct ones).

The product of its digits is 810000, while the sum is 44.

The square root of 66555566 is about 8158.1594738029. The cubic root of 66555566 is about 405.2547622321.

It can be divided in two parts, 6655 and 5566, that added together give a palindrome (12221).

The spelling of 66555566 in words is "sixty-six million, five hundred fifty-five thousand, five hundred sixty-six".