81361281 has 8 divisors (see below), whose sum is σ = 113198400. Its totient is φ = 51882512.

The previous prime is 81361279. The next prime is 81361297. The reversal of 81361281 is 18216318.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81361281 - 2¹ = 81361279 is a prime.

It is a super-2 number, since 2×81361281² = 13239316091921922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81361481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 589506 + ... + 589643.

It is an arithmetic number, because the mean of its divisors is an integer number (14149800).

Almost surely, 2^81361281 is an apocalyptic number.

It is an amenable number.

81361281 is a deficient number, since it is larger than the sum of its proper divisors (31837119).

81361281 is a wasteful number, since it uses less digits than its factorization.

81361281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1179175.

The product of its digits is 2304, while the sum is 30.

The square root of 81361281 is about 9020.0488357880. The cubic root of 81361281 is about 433.3171977555.

Adding to 81361281 its reverse (18216318), we get a palindrome (99577599).

The spelling of 81361281 in words is "eighty-one million, three hundred sixty-one thousand, two hundred eighty-one".