81117080 has 128 divisors (see below), whose sum is σ = 217036800. Its totient is φ = 26956800.

The previous prime is 81117079. The next prime is 81117097. The reversal of 81117080 is 8071118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 259004 + ... + 259316.

It is an arithmetic number, because the mean of its divisors is an integer number (1695600).

Almost surely, 2^81117080 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 81117080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108518400).

81117080 is an abundant number, since it is smaller than the sum of its proper divisors (135919720).

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

81117080 is a wasteful number, since it uses less digits than its factorization.

81117080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385 (or 381 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 26.

The square root of 81117080 is about 9006.5020957084. The cubic root of 81117080 is about 432.8832381133.

Adding to 81117080 its reverse (8071118), we get a palindrome (89188198).

The spelling of 81117080 in words is "eighty-one million, one hundred seventeen thousand, eighty".