81000080 has 80 divisors (see below), whose sum is σ = 217367040. Its totient is φ = 27495936.

The previous prime is 81000077. The next prime is 81000083. The reversal of 81000080 is 8000018.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81000077) and next prime (81000083).

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

It is a super-2 number, since 2×81000080² = 13122025920012800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81000083) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60377 + ... + 61703.

It is an arithmetic number, because the mean of its divisors is an integer number (2717088).

Almost surely, 2^81000080 is an apocalyptic number.

81000080 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 81000080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108683520).

81000080 is an abundant number, since it is smaller than the sum of its proper divisors (136366960).

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

81000080 is a wasteful number, since it uses less digits than its factorization.

81000080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1456 (or 1450 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 81000080 is about 9000.0044444433. The cubic root of 81000080 is about 432.6750135366.

Adding to 81000080 its reverse (8000018), we get a palindrome (89000098).

The spelling of 81000080 in words is "eighty-one million, eighty", and thus it is an aban number and an uban number.