81281231 has 2 divisors, whose sum is σ = 81281232. Its totient is φ = 81281230.

The previous prime is 81281227. The next prime is 81281243. The reversal of 81281231 is 13218218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81281231 - 2² = 81281227 is a prime.

It is a super-2 number, since 2×81281231² = 13213277025750722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81281231.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81281281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40640615 + 40640616.

It is an arithmetic number, because the mean of its divisors is an integer number (40640616).

Almost surely, 2^81281231 is an apocalyptic number.

81281231 is a deficient number, since it is larger than the sum of its proper divisors (1).

81281231 is an equidigital number, since it uses as much as digits as its factorization.

81281231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 26.

The square root of 81281231 is about 9015.6104064007. The cubic root of 81281231 is about 433.1750399483.

Adding to 81281231 its reverse (13218218), we get a palindrome (94499449).

The spelling of 81281231 in words is "eighty-one million, two hundred eighty-one thousand, two hundred thirty-one".