81403185756 has 12 divisors (see below), whose sum is σ = 189940766792. Its totient is φ = 27134395248.

The previous prime is 81403185719. The next prime is 81403185791. The reversal of 81403185756 is 65758130418.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3391799395 + ... + 3391799418.

Almost surely, 2^81403185756 is an apocalyptic number.

It is an amenable number.

81403185756 is an abundant number, since it is smaller than the sum of its proper divisors (108537581036).

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

81403185756 is a wasteful number, since it uses less digits than its factorization.

81403185756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6783598820 (or 6783598818 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 48.

The spelling of 81403185756 in words is "eighty-one billion, four hundred three million, one hundred eighty-five thousand, seven hundred fifty-six".