81594208609 has 9 divisors (see below), whose sum is σ = 83644856211. Its totient is φ = 79592680080.

The previous prime is 81594208583. The next prime is 81594208613. The reversal of 81594208609 is 90680249518.

The square root of 81594208609 is 285647.

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., 3931666209 + 77662542400 = 62703^2 + 278680^2 .

It is not a de Polignac number, because 81594208609 - 2¹³ = 81594200417 is a prime.

It is a super-2 number, since 2×81594208609² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81594208309) 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, 11708044 + ... + 11715010.

Almost surely, 2^81594208609 is an apocalyptic number.

81594208609 is the 285647-th square number.

81594208609 is the 142824-th centered octagonal number.

It is an amenable number.

81594208609 is a deficient number, since it is larger than the sum of its proper divisors (2050647602).

81594208609 is an frugal number, since it uses more digits than its factorization.

81594208609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14016 (or 7008 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 52.

The spelling of 81594208609 in words is "eighty-one billion, five hundred ninety-four million, two hundred eight thousand, six hundred nine".