77775512666 has 4 divisors (see below), whose sum is σ = 116663269002. Its totient is φ = 38887756332.

The previous prime is 77775512663. The next prime is 77775512693. The reversal of 77775512666 is 66621557777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66621557777 = 44071 ⋅1511687.

It can be written as a sum of positive squares in only one way, i.e., 76189800625 + 1585712041 = 276025^2 + 39821^2 .

It is not an unprimeable number, because it can be changed into a prime (77775512663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19443878165 + ... + 19443878168.

Almost surely, 2^77775512666 is an apocalyptic number.

77775512666 is a deficient number, since it is larger than the sum of its proper divisors (38887756336).

77775512666 is a wasteful number, since it uses less digits than its factorization.

77775512666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38887756335.

The product of its digits is 25930800, while the sum is 59.

The spelling of 77775512666 in words is "seventy-seven billion, seven hundred seventy-five million, five hundred twelve thousand, six hundred sixty-six".