81980000 has 60 divisors (see below), whose sum is σ = 201732300. Its totient is φ = 32784000.

The previous prime is 81979999. The next prime is 81980009. The reversal of 81980000 is 8918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81980009) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 17951 + ... + 22049.

It is an arithmetic number, because the mean of its divisors is an integer number (3362205).

Almost surely, 2^81980000 is an apocalyptic number.

81980000 is a gapful number since it is divisible by the number (80) 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 81980000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100866150).

81980000 is an abundant number, since it is smaller than the sum of its proper divisors (119752300).

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

81980000 is an equidigital number, since it uses as much as digits as its factorization.

81980000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4129 (or 4106 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 81980000 is about 9054.2807555322. The cubic root of 81980000 is about 434.4128247172.

Adding to 81980000 its reverse (8918), we get a palindrome (81988918).

The spelling of 81980000 in words is "eighty-one million, nine hundred eighty thousand".