66555664 has 40 divisors (see below), whose sum is σ = 148184960. Its totient is φ = 28366848.

The previous prime is 66555661. The next prime is 66555707. The reversal of 66555664 is 46655566.

It is a self number, because there is not a number n which added to its sum of digits gives 66555664.

It is not an unprimeable number, because it can be changed into a prime (66555661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20077 + ... + 23155.

It is an arithmetic number, because the mean of its divisors is an integer number (3704624).

Almost surely, 2^66555664 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 66555664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (74092480).

66555664 is an abundant number, since it is smaller than the sum of its proper divisors (81629296).

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

66555664 is a wasteful number, since it uses less digits than its factorization.

66555664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3287 (or 3281 counting only the distinct ones).

The product of its digits is 648000, while the sum is 43.

The square root of 66555664 is about 8158.1654800574. The cubic root of 66555664 is about 405.2549611383.

The spelling of 66555664 in words is "sixty-six million, five hundred fifty-five thousand, six hundred sixty-four".