66666564 has 72 divisors (see below), whose sum is σ = 176668128. Its totient is φ = 21980160.

The previous prime is 66666559. The next prime is 66666569. The reversal of 66666564 is 46566666.

It is an interprime number because it is at equal distance from previous prime (66666559) and next prime (66666569).

It is not an unprimeable number, because it can be changed into a prime (66666569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 103684 + ... + 104324.

It is an arithmetic number, because the mean of its divisors is an integer number (2453724).

Almost surely, 2^66666564 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66666564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88334064).

66666564 is an abundant number, since it is smaller than the sum of its proper divisors (110001564).

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

66666564 is a wasteful number, since it uses less digits than its factorization.

66666564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 767 (or 753 counting only the distinct ones).

The product of its digits is 933120, while the sum is 45.

The square root of 66666564 is about 8164.9595222512. The cubic root of 66666564 is about 405.4799248917.

The spelling of 66666564 in words is "sixty-six million, six hundred sixty-six thousand, five hundred sixty-four".