81040080 has 80 divisors (see below), whose sum is σ = 274071744. Its totient is φ = 19645440.

The previous prime is 81040049. The next prime is 81040081. The reversal of 81040080 is 8004018.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81040081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12709 + ... + 17988.

Almost surely, 2^81040080 is an apocalyptic number.

81040080 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81040080 is an abundant number, since it is smaller than the sum of its proper divisors (193031664).

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

81040080 is a wasteful number, since it uses less digits than its factorization.

81040080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30724 (or 30718 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 81040080 is about 9002.2263912879. The cubic root of 81040080 is about 432.7462239701.

Adding to 81040080 its reverse (8004018), we get a palindrome (89044098).

The spelling of 81040080 in words is "eighty-one million, forty thousand, eighty".