66668437728 has 72 divisors (see below), whose sum is σ = 189908566848. Its totient is φ = 22185280512.

The previous prime is 66668437699. The next prime is 66668437733. The reversal of 66668437728 is 82773486666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24400 + ... + 365967.

It is an arithmetic number, because the mean of its divisors is an integer number (2637618984).

Almost surely, 2^66668437728 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 66668437728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94954283424).

66668437728 is an abundant number, since it is smaller than the sum of its proper divisors (123240129120).

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

66668437728 is a wasteful number, since it uses less digits than its factorization.

66668437728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390976 (or 390965 counting only the distinct ones).

The product of its digits is 97542144, while the sum is 63.

The spelling of 66668437728 in words is "sixty-six billion, six hundred sixty-eight million, four hundred thirty-seven thousand, seven hundred twenty-eight".