81442315161 has 45 divisors (see below), whose sum is σ = 125183810829. Its totient is φ = 52765805376.

The previous prime is 81442315153. The next prime is 81442315187. The reversal of 81442315161 is 16151324418.

The square root of 81442315161 is 285381.

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

81442315161 is a `hidden beast` number, since 8 + 1 + 442 + 3 + 151 + 61 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 55139962761 + 26302352400 = 234819^2 + 162180^2 .

It is not a de Polignac number, because 81442315161 - 2³ = 81442315153 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81442315111) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 95031445 + ... + 95032301.

Almost surely, 2^81442315161 is an apocalyptic number.

81442315161 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81442315161 is the 285381-st square number.

81442315161 is the 142691-st centered octagonal number.

It is an amenable number.

81442315161 is a deficient number, since it is larger than the sum of its proper divisors (43741495668).

81442315161 is an frugal number, since it uses more digits than its factorization.

81442315161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800 (or 897 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

Multiplying 81442315161 by its sum of digits (36), we get a square (2931923345796 = 1712286²).

Adding to 81442315161 its reverse (16151324418), we get a palindrome (97593639579).

The spelling of 81442315161 in words is "eighty-one billion, four hundred forty-two million, three hundred fifteen thousand, one hundred sixty-one".