81265818816 has 168 divisors, whose sum is σ = 286687934624. Its totient is φ = 21432729600.

The previous prime is 81265818779. The next prime is 81265818817. The reversal of 81265818816 is 61881856218.

It is a tau number, because it is divible by the number of its divisors (168).

It is not an unprimeable number, because it can be changed into a prime (81265818817) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 722785 + ... + 827616.

Almost surely, 2^81265818816 is an apocalyptic number.

It is an amenable number.

81265818816 is an abundant number, since it is smaller than the sum of its proper divisors (205422115808).

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

81265818816 is a wasteful number, since it uses less digits than its factorization.

81265818816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1550439 (or 1550426 counting only the distinct ones).

The product of its digits is 1474560, while the sum is 54.

The spelling of 81265818816 in words is "eighty-one billion, two hundred sixty-five million, eight hundred eighteen thousand, eight hundred sixteen".