81818135680 has 32 divisors (see below), whose sum is σ = 195596482140. Its totient is φ = 32727254016.

The previous prime is 81818135639. The next prime is 81818135683. The reversal of 81818135680 is 8653181818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 78969992256 + 2848143424 = 281016^2 + 53368^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (81818135683) 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, 63919779 + ... + 63921058.

Almost surely, 2^81818135680 is an apocalyptic number.

81818135680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81818135680 is an abundant number, since it is smaller than the sum of its proper divisors (113778346460).

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

81818135680 is a wasteful number, since it uses less digits than its factorization.

81818135680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127840856 (or 127840844 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 49.

The spelling of 81818135680 in words is "eighty-one billion, eight hundred eighteen million, one hundred thirty-five thousand, six hundred eighty".