66805440 has 224 divisors, whose sum is σ = 235037376. Its totient is φ = 15974400.

The previous prime is 66805433. The next prime is 66805451. The reversal of 66805440 is 4450866.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 661390 + ... + 661490.

It is an arithmetic number, because the mean of its divisors is an integer number (1049274).

Almost surely, 2^66805440 is an apocalyptic number.

66805440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66805440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117518688).

66805440 is an abundant number, since it is smaller than the sum of its proper divisors (168231936).

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

66805440 is a wasteful number, since it uses less digits than its factorization.

66805440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 33.

The square root of 66805440 is about 8173.4594878790. The cubic root of 66805440 is about 405.7612871932.

The spelling of 66805440 in words is "sixty-six million, eight hundred five thousand, four hundred forty".