9981881388 has 18 divisors (see below), whose sum is σ = 25231978044. Its totient is φ = 3327293784.

The previous prime is 9981881387. The next prime is 9981881407. The reversal of 9981881388 is 8831881899.

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (9981881383) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 138637206 + ... + 138637277.

It is an arithmetic number, because the mean of its divisors is an integer number (1401776558).

Almost surely, 2^9981881388 is an apocalyptic number.

It is an amenable number.

9981881388 is an abundant number, since it is smaller than the sum of its proper divisors (15250096656).

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

9981881388 is a wasteful number, since it uses less digits than its factorization.

9981881388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277274493 (or 277274488 counting only the distinct ones).

The product of its digits is 7962624, while the sum is 63.

The square root of 9981881388 is about 99909.3658672699. The cubic root of 9981881388 is about 2153.1327245138.

The spelling of 9981881388 in words is "nine billion, nine hundred eighty-one million, eight hundred eighty-one thousand, three hundred eighty-eight".