66666864 has 80 divisors (see below), whose sum is σ = 193987584. Its totient is φ = 19545600.

The previous prime is 66666863. The next prime is 66666869. The reversal of 66666864 is 46866666.

66666864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66666863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14332 + ... + 18404.

Almost surely, 2^66666864 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 66666864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96993792).

66666864 is an abundant number, since it is smaller than the sum of its proper divisors (127320720).

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

66666864 is a wasteful number, since it uses less digits than its factorization.

66666864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4126 (or 4120 counting only the distinct ones).

The product of its digits is 1492992, while the sum is 48.

The square root of 66666864 is about 8164.9778934177. The cubic root of 66666864 is about 405.4805331116.

It can be divided in two parts, 6666 and 6864, that added together give a triangular number (13530 = T₁₆₄).

The spelling of 66666864 in words is "sixty-six million, six hundred sixty-six thousand, eight hundred sixty-four".