1981328688 has 140 divisors (see below), whose sum is σ = 5912447968. Its totient is φ = 642453120.

The previous prime is 1981328681. The next prime is 1981328717. The reversal of 1981328688 is 8868231891.

It is a super-3 number, since 3×1981328688³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1981328681) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 429273 + ... + 433863.

Almost surely, 2^1981328688 is an apocalyptic number.

1981328688 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1981328688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2956223984).

1981328688 is an abundant number, since it is smaller than the sum of its proper divisors (3931119280).

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

1981328688 is an equidigital number, since it uses as much as digits as its factorization.

1981328688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4654 (or 4633 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 54.

The square root of 1981328688 is about 44512.1184398137. The cubic root of 1981328688 is about 1255.9880555209.

The spelling of 1981328688 in words is "one billion, nine hundred eighty-one million, three hundred twenty-eight thousand, six hundred eighty-eight".