81344249281 has 4 divisors (see below), whose sum is σ = 82258229700. Its totient is φ = 80430268864.

The previous prime is 81344249243. The next prime is 81344249317. The reversal of 81344249281 is 18294244318.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 41783039281 + 39561210000 = 204409^2 + 198900^2 .

It is a cyclic number.

It is not a de Polignac number, because 81344249281 - 2⁷ = 81344249153 is a prime.

It is a super-2 number, since 2×81344249281² (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 (81344249881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 456990076 + ... + 456990253.

It is an arithmetic number, because the mean of its divisors is an integer number (20564557425).

Almost surely, 2^81344249281 is an apocalyptic number.

It is an amenable number.

81344249281 is a deficient number, since it is larger than the sum of its proper divisors (913980419).

81344249281 is an equidigital number, since it uses as much as digits as its factorization.

81344249281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913980418.

The product of its digits is 442368, while the sum is 46.

It can be divided in two parts, 81344 and 249281, that added together give a square (330625 = 575²).

The spelling of 81344249281 in words is "eighty-one billion, three hundred forty-four million, two hundred forty-nine thousand, two hundred eighty-one".