81043540 has 24 divisors (see below), whose sum is σ = 170950752. Its totient is φ = 32272800.

The previous prime is 81043537. The next prime is 81043549. The reversal of 81043540 is 4534018.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81043549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4386 + ... + 13465.

It is an arithmetic number, because the mean of its divisors is an integer number (7122948).

Almost surely, 2^81043540 is an apocalyptic number.

It is an amenable number.

81043540 is an abundant number, since it is smaller than the sum of its proper divisors (89907212).

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

81043540 is a wasteful number, since it uses less digits than its factorization.

81043540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18087 (or 18085 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 81043540 is about 9002.4185639194. The cubic root of 81043540 is about 432.7523825714.

Adding to 81043540 its reverse (4534018), we get a palindrome (85577558).

The spelling of 81043540 in words is "eighty-one million, forty-three thousand, five hundred forty".