81126709 has 2 divisors, whose sum is σ = 81126710. Its totient is φ = 81126708.

The previous prime is 81126707. The next prime is 81126733. The reversal of 81126709 is 90762118.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61074225 + 20052484 = 7815^2 + 4478^2 .

It is a cyclic number.

It is not a de Polignac number, because 81126709 - 2¹ = 81126707 is a prime.

Together with 81126707, 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 (81126701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40563354 + 40563355.

It is an arithmetic number, because the mean of its divisors is an integer number (40563355).

Almost surely, 2^81126709 is an apocalyptic number.

It is an amenable number.

81126709 is a deficient number, since it is larger than the sum of its proper divisors (1).

81126709 is an equidigital number, since it uses as much as digits as its factorization.

81126709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 81126709 is about 9007.0366380958. The cubic root of 81126709 is about 432.9003658986.

The spelling of 81126709 in words is "eighty-one million, one hundred twenty-six thousand, seven hundred nine".