81131319040 has 72 divisors (see below), whose sum is σ = 194384424528. Its totient is φ = 32444252160.

The previous prime is 81131319011. The next prime is 81131319041. The reversal of 81131319040 is 4091313118.

It is a junction number, because it is equal to n+sod(n) for n = 81131318993 and 81131319011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81131319041) 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, 8559744 + ... + 8569216.

It is an arithmetic number, because the mean of its divisors is an integer number (2699783674).

Almost surely, 2^81131319040 is an apocalyptic number.

81131319040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81131319040 is an abundant number, since it is smaller than the sum of its proper divisors (113253105488).

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

81131319040 is an equidigital number, since it uses as much as digits as its factorization.

81131319040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16185 (or 16171 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The spelling of 81131319040 in words is "eighty-one billion, one hundred thirty-one million, three hundred nineteen thousand, forty".