66556778 has 8 divisors (see below), whose sum is σ = 100823940. Its totient is φ = 32948800.

The previous prime is 66556757. The next prime is 66556793. The reversal of 66556778 is 87765566.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 60171049 + 6385729 = 7757^2 + 2527^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 164543 + ... + 164946.

Almost surely, 2^66556778 is an apocalyptic number.

66556778 is a deficient number, since it is larger than the sum of its proper divisors (34267162).

66556778 is a wasteful number, since it uses less digits than its factorization.

66556778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329592.

The product of its digits is 2116800, while the sum is 50.

The square root of 66556778 is about 8158.2337549251. The cubic root of 66556778 is about 405.2572221605.

The spelling of 66556778 in words is "sixty-six million, five hundred fifty-six thousand, seven hundred seventy-eight".