81747856944 has 120 divisors (see below), whose sum is σ = 246463096880. Its totient is φ = 25144598016.

The previous prime is 81747856907. The next prime is 81747856963. The reversal of 81747856944 is 44965874718.

It is a super-2 number, since 2×81747856944² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7488162 + ... + 7499070.

Almost surely, 2^81747856944 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81747856944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123231548440).

81747856944 is an abundant number, since it is smaller than the sum of its proper divisors (164715239936).

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

81747856944 is a wasteful number, since it uses less digits than its factorization.

81747856944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14939 (or 14930 counting only the distinct ones).

The product of its digits is 54190080, while the sum is 63.

The spelling of 81747856944 in words is "eighty-one billion, seven hundred forty-seven million, eight hundred fifty-six thousand, nine hundred forty-four".