66778423524 has 18 divisors (see below), whose sum is σ = 168801015110. Its totient is φ = 22259474496.

The previous prime is 66778423441. The next prime is 66778423559. The reversal of 66778423524 is 42532487766.

66778423524 is a `hidden beast` number, since 6 + 6 + 7 + 78 + 42 + 3 + 524 = 666.

66778423524 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 only one way, i.e., 59478429924 + 7299993600 = 243882^2 + 85440^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 927478069 + ... + 927478140.

Almost surely, 2^66778423524 is an apocalyptic number.

It is an amenable number.

66778423524 is an abundant number, since it is smaller than the sum of its proper divisors (102022591586).

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

66778423524 is a wasteful number, since it uses less digits than its factorization.

66778423524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1854956219 (or 1854956214 counting only the distinct ones).

The product of its digits is 13547520, while the sum is 54.

The spelling of 66778423524 in words is "sixty-six billion, seven hundred seventy-eight million, four hundred twenty-three thousand, five hundred twenty-four".