81321269 has 2 divisors, whose sum is σ = 81321270. Its totient is φ = 81321268.

The previous prime is 81321223. The next prime is 81321287. The reversal of 81321269 is 96212318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79032100 + 2289169 = 8890^2 + 1513^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81321269 is a prime.

It is a super-2 number, since 2×81321269² = 13226297583540722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81320269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40660634 + 40660635.

It is an arithmetic number, because the mean of its divisors is an integer number (40660635).

Almost surely, 2^81321269 is an apocalyptic number.

It is an amenable number.

81321269 is a deficient number, since it is larger than the sum of its proper divisors (1).

81321269 is an equidigital number, since it uses as much as digits as its factorization.

81321269 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 81321269 is about 9017.8306149539. The cubic root of 81321269 is about 433.2461535994.

The spelling of 81321269 in words is "eighty-one million, three hundred twenty-one thousand, two hundred sixty-nine".