81481892560 has 20 divisors (see below), whose sum is σ = 189445400388. Its totient is φ = 32592756992.

The previous prime is 81481892543. The next prime is 81481892561. The reversal of 81481892560 is 6529818418.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 61262190144 + 20219702416 = 247512^2 + 142196^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 81481892498 and 81481892507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81481892561) 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, 509261749 + ... + 509261908.

Almost surely, 2^81481892560 is an apocalyptic number.

81481892560 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81481892560 is an abundant number, since it is smaller than the sum of its proper divisors (107963507828).

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

81481892560 is a wasteful number, since it uses less digits than its factorization.

81481892560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018523670 (or 1018523664 counting only the distinct ones).

The product of its (nonzero) digits is 1105920, while the sum is 52.

The spelling of 81481892560 in words is "eighty-one billion, four hundred eighty-one million, eight hundred ninety-two thousand, five hundred sixty".