81983988 has 60 divisors (see below), whose sum is σ = 217103040. Its totient is φ = 26973648.

The previous prime is 81983963. The next prime is 81983989. The reversal of 81983988 is 88938918.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81983989) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 23995 + ... + 27197.

It is an arithmetic number, because the mean of its divisors is an integer number (3618384).

Almost surely, 2^81983988 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81983988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108551520).

81983988 is an abundant number, since it is smaller than the sum of its proper divisors (135119052).

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

81983988 is a wasteful number, since it uses less digits than its factorization.

81983988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3298 (or 3287 counting only the distinct ones).

The product of its digits is 995328, while the sum is 54.

The square root of 81983988 is about 9054.5009801756. The cubic root of 81983988 is about 434.4198687533.

The spelling of 81983988 in words is "eighty-one million, nine hundred eighty-three thousand, nine hundred eighty-eight".