1988897778 has 192 divisors, whose sum is σ = 5360808960. Its totient is φ = 520805376.

The previous prime is 1988897737. The next prime is 1988897809. The reversal of 1988897778 is 8777988891.

It is a happy number.

Its product of digits (113799168) is a multiple of the sum of its prime factors (441).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 6354150 + ... + 6354462.

It is an arithmetic number, because the mean of its divisors is an integer number (27920880).

Almost surely, 2^1988897778 is an apocalyptic number.

1988897778 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 1988897778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2680404480).

1988897778 is an abundant number, since it is smaller than the sum of its proper divisors (3371911182).

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

1988897778 is a wasteful number, since it uses less digits than its factorization.

1988897778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441 (or 438 counting only the distinct ones).

The product of its digits is 113799168, while the sum is 72.

The square root of 1988897778 is about 44597.0601945913. The cubic root of 1988897778 is about 1257.5854022025.

The spelling of 1988897778 in words is "one billion, nine hundred eighty-eight million, eight hundred ninety-seven thousand, seven hundred seventy-eight".