81272436309 has 12 divisors (see below), whose sum is σ = 117413503116. Its totient is φ = 54172400832.

The previous prime is 81272436277. The next prime is 81272436361. The reversal of 81272436309 is 90363427218.

81272436309 is a `hidden beast` number, since 8 + 1 + 2 + 7 + 2 + 4 + 3 + 630 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 39619708209 + 41652728100 = 199047^2 + 204090^2 .

It is not a de Polignac number, because 81272436309 - 2⁵ = 81272436277 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81272436379) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 712594 + ... + 818739.

It is an arithmetic number, because the mean of its divisors is an integer number (9784458593).

Almost surely, 2^81272436309 is an apocalyptic number.

It is an amenable number.

81272436309 is a deficient number, since it is larger than the sum of its proper divisors (36141066807).

81272436309 is a wasteful number, since it uses less digits than its factorization.

81272436309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1537236 (or 1537233 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

Subtracting 81272436309 from its reverse (90363427218), we obtain a palindrome (9090990909).

It can be divided in two parts, 812 and 72436309, that added together give a square (72437121 = 8511²).

The spelling of 81272436309 in words is "eighty-one billion, two hundred seventy-two million, four hundred thirty-six thousand, three hundred nine".