81256672456 has 16 divisors (see below), whose sum is σ = 152988448140. Its totient is φ = 40459752960.

The previous prime is 81256672429. The next prime is 81256672457. The reversal of 81256672456 is 65427665218.

It can be written as a sum of positive squares in 2 ways, for example, as 76856472900 + 4400199556 = 277230^2 + 66334^2 .

It is not an unprimeable number, because it can be changed into a prime (81256672457) 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, 21070861 + ... + 21074716.

Almost surely, 2^81256672456 is an apocalyptic number.

It is an amenable number.

81256672456 is a deficient number, since it is larger than the sum of its proper divisors (71731775684).

81256672456 is a wasteful number, since it uses less digits than its factorization.

81256672456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42145824 (or 42145820 counting only the distinct ones).

The product of its digits is 4838400, while the sum is 52.

The spelling of 81256672456 in words is "eighty-one billion, two hundred fifty-six million, six hundred seventy-two thousand, four hundred fifty-six".