66115566 has 48 divisors (see below), whose sum is σ = 157068288. Its totient is φ = 19933200.

The previous prime is 66115541. The next prime is 66115603. The reversal of 66115566 is 66551166.

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66115566.

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, 44211 + ... + 45681.

It is an arithmetic number, because the mean of its divisors is an integer number (3272256).

Almost surely, 2^66115566 is an apocalyptic number.

66115566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 66115566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78534144).

66115566 is an abundant number, since it is smaller than the sum of its proper divisors (90952722).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66115566 is a wasteful number, since it uses less digits than its factorization.

66115566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1717 (or 1714 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 66115566 is about 8131.1478894434. The cubic root of 66115566 is about 404.3597382336.

Subtracting 66115566 from its reverse (66551166), we obtain a square (435600 = 660²).

The spelling of 66115566 in words is "sixty-six million, one hundred fifteen thousand, five hundred sixty-six".