81951085441 has 9 divisors (see below), whose sum is σ = 82261139331. Its totient is φ = 81642199032.

The previous prime is 81951085357. The next prime is 81951085451. The reversal of 81951085441 is 14458015918.

The square root of 81951085441 is 286271.

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., 267159025 + 81683926416 = 16345^2 + 285804^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81951085441 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81951085391 and 81951085400.

It is not an unprimeable number, because it can be changed into a prime (81951085451) 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, 133688251 + ... + 133688863.

Almost surely, 2^81951085441 is an apocalyptic number.

81951085441 is the 286271-st square number.

81951085441 is the 143136-th centered octagonal number.

It is an amenable number.

81951085441 is a deficient number, since it is larger than the sum of its proper divisors (310053890).

81951085441 is an frugal number, since it uses more digits than its factorization.

81951085441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2160 (or 1080 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 46.

The spelling of 81951085441 in words is "eighty-one billion, nine hundred fifty-one million, eighty-five thousand, four hundred forty-one".