81226261 has 2 divisors, whose sum is σ = 81226262. Its totient is φ = 81226260.

The previous prime is 81226259. The next prime is 81226291. The reversal of 81226261 is 16262218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75585636 + 5640625 = 8694^2 + 2375^2 .

It is a cyclic number.

It is not a de Polignac number, because 81226261 - 2¹ = 81226259 is a prime.

Together with 81226259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81226241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40613130 + 40613131.

It is an arithmetic number, because the mean of its divisors is an integer number (40613131).

Almost surely, 2^81226261 is an apocalyptic number.

It is an amenable number.

81226261 is a deficient number, since it is larger than the sum of its proper divisors (1).

81226261 is an equidigital number, since it uses as much as digits as its factorization.

81226261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 28.

The square root of 81226261 is about 9012.5612896668. The cubic root of 81226261 is about 433.0773667153.

Adding to 81226261 its reverse (16262218), we get a palindrome (97488479).

The spelling of 81226261 in words is "eighty-one million, two hundred twenty-six thousand, two hundred sixty-one".