81413909 has 2 divisors, whose sum is σ = 81413910. Its totient is φ = 81413908.

The previous prime is 81413903. The next prime is 81413929. The reversal of 81413909 is 90931418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 60684100 + 20729809 = 7790^2 + 4553^2 .

It is a cyclic number.

It is not a de Polignac number, because 81413909 - 2²⁰ = 80365333 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81413903) 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 as a sum of consecutive naturals, namely, 40706954 + 40706955.

It is an arithmetic number, because the mean of its divisors is an integer number (40706955).

Almost surely, 2^81413909 is an apocalyptic number.

It is an amenable number.

81413909 is a deficient number, since it is larger than the sum of its proper divisors (1).

81413909 is an equidigital number, since it uses as much as digits as its factorization.

81413909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 81413909 is about 9022.9656432905. The cubic root of 81413909 is about 433.4106070610.

The spelling of 81413909 in words is "eighty-one million, four hundred thirteen thousand, nine hundred nine".