78691390866 has 32 divisors (see below), whose sum is σ = 190767009600. Its totient is φ = 23845875840.

The previous prime is 78691390801. The next prime is 78691390867. The reversal of 78691390866 is 66809319687.

78691390866 is a `hidden beast` number, since 7 + 86 + 91 + 390 + 86 + 6 = 666.

It is not an unprimeable number, because it can be changed into a prime (78691390867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66237951 + ... + 66239138.

It is an arithmetic number, because the mean of its divisors is an integer number (5961469050).

Almost surely, 2^78691390866 is an apocalyptic number.

78691390866 is an abundant number, since it is smaller than the sum of its proper divisors (112075618734).

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

78691390866 is a wasteful number, since it uses less digits than its factorization.

78691390866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132477111 (or 132477105 counting only the distinct ones).

The product of its (nonzero) digits is 23514624, while the sum is 63.

The spelling of 78691390866 in words is "seventy-eight billion, six hundred ninety-one million, three hundred ninety thousand, eight hundred sixty-six".