81161172544 has 63 divisors (see below), whose sum is σ = 162823615297. Its totient is φ = 40139579648.

The previous prime is 81161172541. The next prime is 81161172569. The reversal of 81161172544 is 44527116118.

The square root of 81161172544 is 284888.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 9508590144 + 71652582400 = 97512^2 + 267680^2 .

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81161172497 and 81161172506.

It is not an unprimeable number, because it can be changed into a prime (81161172541) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 339586377 + ... + 339586615.

Almost surely, 2^81161172544 is an apocalyptic number.

81161172544 is the 284888-th square number.

It is an amenable number.

81161172544 is an abundant number, since it is smaller than the sum of its proper divisors (81662442753).

81161172544 is an frugal number, since it uses more digits than its factorization.

81161172544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788 (or 390 counting only the distinct ones).

The product of its digits is 53760, while the sum is 40.

The spelling of 81161172544 in words is "eighty-one billion, one hundred sixty-one million, one hundred seventy-two thousand, five hundred forty-four".