1986481778778 has 128 divisors (see below), whose sum is σ = 5235472627200. Its totient is φ = 546265327104.

The previous prime is 1986481778777. The next prime is 1986481778779. The reversal of 1986481778778 is 8778771846891.

It is an interprime number because it is at equal distance from previous prime (1986481778777) and next prime (1986481778779).

It is a super-2 number, since 2×1986481778778² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1986481778697 and 1986481778706.

It is not an unprimeable number, because it can be changed into a prime (1986481778777) 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 63 ways as a sum of consecutive naturals, for example, 3189126 + ... + 3760782.

It is an arithmetic number, because the mean of its divisors is an integer number (40902129900).

Almost surely, 2^{1986481778778} is an apocalyptic number.

1986481778778 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1986481778778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2617736313600).

1986481778778 is an abundant number, since it is smaller than the sum of its proper divisors (3248990848422).

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

1986481778778 is a wasteful number, since it uses less digits than its factorization.

1986481778778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572021 (or 572015 counting only the distinct ones).

The product of its digits is 2124251136, while the sum is 81.

The spelling of 1986481778778 in words is "one trillion, nine hundred eighty-six billion, four hundred eighty-one million, seven hundred seventy-eight thousand, seven hundred seventy-eight".