77771686 has 4 divisors (see below), whose sum is σ = 116657532. Its totient is φ = 38885842.

The previous prime is 77771663. The next prime is 77771689. The reversal of 77771686 is 68617777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68617777 = 4871 ⋅14087.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77771689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19442920 + ... + 19442923.

It is an arithmetic number, because the mean of its divisors is an integer number (29164383).

Almost surely, 2^77771686 is an apocalyptic number.

77771686 is a deficient number, since it is larger than the sum of its proper divisors (38885846).

77771686 is a wasteful number, since it uses less digits than its factorization.

77771686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38885845.

The product of its digits is 691488, while the sum is 49.

The square root of 77771686 is about 8818.8256587825. The cubic root of 77771686 is about 426.8485770805.

The spelling of 77771686 in words is "seventy-seven million, seven hundred seventy-one thousand, six hundred eighty-six".