81643347289 has 9 divisors (see below), whose sum is σ = 94975200117. Its totient is φ = 69978297564.

The previous prime is 81643347283. The next prime is 81643347361. The reversal of 81643347289 is 98274334618.

The square root of 81643347289 is 285733.

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

It is not a de Polignac number, because 81643347289 - 2⁹ = 81643346777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81643347283) 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, 1979722 + ... + 2020540.

It is an arithmetic number, because the mean of its divisors is an integer number (10552800013).

Almost surely, 2^81643347289 is an apocalyptic number.

81643347289 is the 285733-rd square number.

81643347289 is the 142867-th centered octagonal number.

It is an amenable number.

81643347289 is a deficient number, since it is larger than the sum of its proper divisors (13331852828).

81643347289 is an frugal number, since it uses more digits than its factorization.

81643347289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81652 (or 40826 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 55.

The spelling of 81643347289 in words is "eighty-one billion, six hundred forty-three million, three hundred forty-seven thousand, two hundred eighty-nine".