66091780 has 12 divisors (see below), whose sum is σ = 138792780. Its totient is φ = 26436704.

The previous prime is 66091777. The next prime is 66091787. The reversal of 66091780 is 8719066.

66091780 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 42588676 + 23503104 = 6526^2 + 4848^2 .

It is not an unprimeable number, because it can be changed into a prime (66091787) 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 3 ways as a sum of consecutive naturals, for example, 1652275 + ... + 1652314.

It is an arithmetic number, because the mean of its divisors is an integer number (11566065).

Almost surely, 2^66091780 is an apocalyptic number.

It is an amenable number.

66091780 is an abundant number, since it is smaller than the sum of its proper divisors (72701000).

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

66091780 is a wasteful number, since it uses less digits than its factorization.

66091780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3304598 (or 3304596 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 66091780 is about 8129.6851107531. The cubic root of 66091780 is about 404.3112410593.

The spelling of 66091780 in words is "sixty-six million, ninety-one thousand, seven hundred eighty".