861131778 has 16 divisors (see below), whose sum is σ = 1854745536. Its totient is φ = 264963600.

The previous prime is 861131731. The next prime is 861131797. The reversal of 861131778 is 877131168.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 5519998 + ... + 5520153.

It is an arithmetic number, because the mean of its divisors is an integer number (115921596).

Almost surely, 2^861131778 is an apocalyptic number.

861131778 is an abundant number, since it is smaller than the sum of its proper divisors (993613758).

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

861131778 is a wasteful number, since it uses less digits than its factorization.

861131778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11040169.

The product of its digits is 56448, while the sum is 42.

The square root of 861131778 is about 29345.0469074425. The cubic root of 861131778 is about 951.3855232751.

The spelling of 861131778 in words is "eight hundred sixty-one million, one hundred thirty-one thousand, seven hundred seventy-eight".