1986686778 has 32 divisors (see below), whose sum is σ = 4364352000. Its totient is φ = 600096816.

The previous prime is 1986686771. The next prime is 1986686803. The reversal of 1986686778 is 8776866891.

It is not an unprimeable number, because it can be changed into a prime (1986686771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 376228 + ... + 381471.

It is an arithmetic number, because the mean of its divisors is an integer number (136386000).

Almost surely, 2^1986686778 is an apocalyptic number.

1986686778 is an abundant number, since it is smaller than the sum of its proper divisors (2377665222).

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

1986686778 is a wasteful number, since it uses less digits than its factorization.

1986686778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 757746.

The product of its digits is 48771072, while the sum is 66.

The square root of 1986686778 is about 44572.2646721030. The cubic root of 1986686778 is about 1257.1192223358.

The spelling of 1986686778 in words is "one billion, nine hundred eighty-six million, six hundred eighty-six thousand, seven hundred seventy-eight".