866786278380778 has 12 divisors (see below), whose sum is σ = 1512453608195202. Its totient is φ = 371479833591720.

The previous prime is 866786278380739. The next prime is 866786278380809. The reversal of 866786278380778 is 877083872687668.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 662428017356329 + 204358261024449 = 25737677^2 + 14295393^2 .

It is a junction number, because it is equal to n+sod(n) for n = 866786278380692 and 866786278380701.

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, 4422378971233 + ... + 4422378971428.

Almost surely, 2^{866786278380778} is an apocalyptic number.

866786278380778 is a deficient number, since it is larger than the sum of its proper divisors (645667329814424).

866786278380778 is a wasteful number, since it uses less digits than its factorization.

866786278380778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8844757942677 (or 8844757942670 counting only the distinct ones).

The product of its (nonzero) digits is 101964054528, while the sum is 91.

The spelling of 866786278380778 in words is "eight hundred sixty-six trillion, seven hundred eighty-six billion, two hundred seventy-eight million, three hundred eighty thousand, seven hundred seventy-eight".