66381780 has 24 divisors (see below), whose sum is σ = 185869152. Its totient is φ = 17701792.

The previous prime is 66381773. The next prime is 66381781. The reversal of 66381780 is 8718366.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66381781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 553122 + ... + 553241.

It is an arithmetic number, because the mean of its divisors is an integer number (7744548).

Almost surely, 2^66381780 is an apocalyptic number.

66381780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66381780 is an abundant number, since it is smaller than the sum of its proper divisors (119487372).

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

66381780 is a wasteful number, since it uses less digits than its factorization.

66381780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1106375 (or 1106373 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 66381780 is about 8147.5014575022. The cubic root of 66381780 is about 404.9017289386.

It can be divided in two parts, 66381 and 780, that added together give a triangular number (67161 = T₃₆₆).

The spelling of 66381780 in words is "sixty-six million, three hundred eighty-one thousand, seven hundred eighty".