66780358205625 has 45 divisors (see below), whose sum is σ = 120538168824073. Its totient is φ = 35615864166000.

The previous prime is 66780358205581. The next prime is 66780358205647. The reversal of 66780358205625 is 52650285308766.

The square root of 66780358205625 is 8171925.

It is a perfect power (a square), and thus also a powerful number.

66780358205625 is a `hidden beast` number, since 6 + 6 + 78 + 0 + 358 + 205 + 6 + 2 + 5 = 666.

66780358205625 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 5235580083321 + 61544778122304 = 2288139^2 + 7845048^2 .

It is a tau number, because it is divible by the number of its divisors (45).

It is not a de Polignac number, because 66780358205625 - 2³¹ = 66778210721977 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 612839896 + ... + 612948854.

Almost surely, 2^{66780358205625} is an apocalyptic number.

66780358205625 is the 8171925-th square number.

66780358205625 is the 4085963-rd centered octagonal number.

It is an amenable number.

66780358205625 is a deficient number, since it is larger than the sum of its proper divisors (53757810618448).

66780358205625 is an frugal number, since it uses more digits than its factorization.

66780358205625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217944 (or 108967 counting only the distinct ones).

The product of its (nonzero) digits is 145152000, while the sum is 63.

The spelling of 66780358205625 in words is "sixty-six trillion, seven hundred eighty billion, three hundred fifty-eight million, two hundred five thousand, six hundred twenty-five".