81120780 has 72 divisors (see below), whose sum is σ = 265002192. Its totient is φ = 19967616.

The previous prime is 81120763. The next prime is 81120791. The reversal of 81120780 is 8702118.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14994 + ... + 19673.

It is an arithmetic number, because the mean of its divisors is an integer number (3680586).

Almost surely, 2^81120780 is an apocalyptic number.

It is an amenable number.

81120780 is an abundant number, since it is smaller than the sum of its proper divisors (183881412).

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

81120780 is a wasteful number, since it uses less digits than its factorization.

81120780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34695 (or 34690 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 81120780 is about 9006.7075005243. The cubic root of 81120780 is about 432.8898197261.

Adding to 81120780 its reverse (8702118), we get a palindrome (89822898).

The spelling of 81120780 in words is "eighty-one million, one hundred twenty thousand, seven hundred eighty".