66121728 has 52 divisors (see below), whose sum is σ = 176335848. Its totient is φ = 22036480.

The previous prime is 66121681. The next prime is 66121733. The reversal of 66121728 is 82712166.

It is a zygodrome in base 2 and base 4.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9598 + ... + 14978.

It is an arithmetic number, because the mean of its divisors is an integer number (3391074).

Almost surely, 2^66121728 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 66121728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88167924).

66121728 is an abundant number, since it is smaller than the sum of its proper divisors (110214120).

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

66121728 is an equidigital number, since it uses as much as digits as its factorization.

66121728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5408 (or 5386 counting only the distinct ones).

The product of its digits is 8064, while the sum is 33.

The square root of 66121728 is about 8131.5267939053. The cubic root of 66121728 is about 404.3723000122.

The spelling of 66121728 in words is "sixty-six million, one hundred twenty-one thousand, seven hundred twenty-eight".