81168811540 has 24 divisors (see below), whose sum is σ = 174418564320. Its totient is φ = 31712465568.

The previous prime is 81168811523. The next prime is 81168811543. The reversal of 81168811540 is 4511886118.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81168811543) 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, 47190310 + ... + 47192029.

It is an arithmetic number, because the mean of its divisors is an integer number (7267440180).

Almost surely, 2^81168811540 is an apocalyptic number.

It is an amenable number.

81168811540 is an abundant number, since it is smaller than the sum of its proper divisors (93249752780).

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

81168811540 is a wasteful number, since it uses less digits than its factorization.

81168811540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94382391 (or 94382389 counting only the distinct ones).

The product of its (nonzero) digits is 61440, while the sum is 43.

The spelling of 81168811540 in words is "eighty-one billion, one hundred sixty-eight million, eight hundred eleven thousand, five hundred forty".