66780880 has 20 divisors (see below), whose sum is σ = 155265732. Its totient is φ = 26712320.

The previous prime is 66780871. The next prime is 66780899. The reversal of 66780880 is 8808766.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 12787776 + 53993104 = 3576^2 + 7348^2 .

It is a tau number, because it is divible by the number of its divisors (20).

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, 417301 + ... + 417460.

Almost surely, 2^66780880 is an apocalyptic number.

It is an amenable number.

66780880 is an abundant number, since it is smaller than the sum of its proper divisors (88484852).

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

66780880 is a wasteful number, since it uses less digits than its factorization.

66780880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 834774 (or 834768 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 43.

The square root of 66780880 is about 8171.9569259756. The cubic root of 66780880 is about 405.7115571179.

The spelling of 66780880 in words is "sixty-six million, seven hundred eighty thousand, eight hundred eighty".