1986122778 has 16 divisors (see below), whose sum is σ = 4079604000. Its totient is φ = 644147856.

The previous prime is 1986122777. The next prime is 1986122791. The reversal of 1986122778 is 8772216891.

It is a self number, because there is not a number n which added to its sum of digits gives 1986122778.

It is not an unprimeable number, because it can be changed into a prime (1986122771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4473028 + ... + 4473471.

It is an arithmetic number, because the mean of its divisors is an integer number (254975250).

Almost surely, 2^1986122778 is an apocalyptic number.

1986122778 is an abundant number, since it is smaller than the sum of its proper divisors (2093481222).

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

1986122778 is a wasteful number, since it uses less digits than its factorization.

1986122778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8946541.

The product of its digits is 677376, while the sum is 51.

The square root of 1986122778 is about 44565.9374186160. The cubic root of 1986122778 is about 1257.0002499922. Note that the first 3 decimals are identical.

The spelling of 1986122778 in words is "one billion, nine hundred eighty-six million, one hundred twenty-two thousand, seven hundred seventy-eight".