81381684540 has 96 divisors (see below), whose sum is σ = 245445189696. Its totient is φ = 20028487680.

The previous prime is 81381684533. The next prime is 81381684547. The reversal of 81381684540 is 4548618318.

It is an interprime number because it is at equal distance from previous prime (81381684533) and next prime (81381684547).

It is a self number, because there is not a number n which added to its sum of digits gives 81381684540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81381684547) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7577014 + ... + 7587746.

It is an arithmetic number, because the mean of its divisors is an integer number (2556720726).

Almost surely, 2^81381684540 is an apocalyptic number.

It is an amenable number.

81381684540 is an abundant number, since it is smaller than the sum of its proper divisors (164063505156).

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

81381684540 is a wasteful number, since it uses less digits than its factorization.

81381684540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20479 (or 20477 counting only the distinct ones).

The product of its (nonzero) digits is 737280, while the sum is 48.

The spelling of 81381684540 in words is "eighty-one billion, three hundred eighty-one million, six hundred eighty-four thousand, five hundred forty".