81589645913 has 2 divisors, whose sum is σ = 81589645914. Its totient is φ = 81589645912.

The previous prime is 81589645909. The next prime is 81589645981. The reversal of 81589645913 is 31954698518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46533824089 + 35055821824 = 215717^2 + 187232^2 .

It is a cyclic number.

It is not a de Polignac number, because 81589645913 - 2² = 81589645909 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81589645013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40794822956 + 40794822957.

It is an arithmetic number, because the mean of its divisors is an integer number (40794822957).

Almost surely, 2^81589645913 is an apocalyptic number.

It is an amenable number.

81589645913 is a deficient number, since it is larger than the sum of its proper divisors (1).

81589645913 is an equidigital number, since it uses as much as digits as its factorization.

81589645913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9331200, while the sum is 59.

The spelling of 81589645913 in words is "eighty-one billion, five hundred eighty-nine million, six hundred forty-five thousand, nine hundred thirteen".