66544566 has 64 divisors (see below), whose sum is σ = 154275840. Its totient is φ = 18935840.

The previous prime is 66544561. The next prime is 66544603.

It is a happy number.

66544566 is nontrivially palindromic in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66544561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 89191 + ... + 89933.

It is an arithmetic number, because the mean of its divisors is an integer number (2410560).

Almost surely, 2^66544566 is an apocalyptic number.

66544566 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 66544566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77137920).

66544566 is an abundant number, since it is smaller than the sum of its proper divisors (87731274).

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

66544566 is a wasteful number, since it uses less digits than its factorization.

66544566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 841.

The product of its digits is 518400, while the sum is 42.

The square root of 66544566 is about 8157.4852742742. The cubic root of 66544566 is about 405.2324347832.

The spelling of 66544566 in words is "sixty-six million, five hundred forty-four thousand, five hundred sixty-six".