81181340 has 12 divisors (see below), whose sum is σ = 170480856. Its totient is φ = 32472528.

The previous prime is 81181313. The next prime is 81181349. The reversal of 81181340 is 4318118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81181349) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2029514 + ... + 2029553.

It is an arithmetic number, because the mean of its divisors is an integer number (14206738).

Almost surely, 2^81181340 is an apocalyptic number.

It is an amenable number.

81181340 is an abundant number, since it is smaller than the sum of its proper divisors (89299516).

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

81181340 is a wasteful number, since it uses less digits than its factorization.

81181340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4059076 (or 4059074 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 81181340 is about 9010.0688121679. The cubic root of 81181340 is about 432.9975162845.

Adding to 81181340 its reverse (4318118), we get a palindrome (85499458).

The spelling of 81181340 in words is "eighty-one million, one hundred eighty-one thousand, three hundred forty".