81985650113 has 2 divisors, whose sum is σ = 81985650114. Its totient is φ = 81985650112.

The previous prime is 81985650091. The next prime is 81985650139. The reversal of 81985650113 is 31105658918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81812016784 + 173633329 = 286028^2 + 13177^2 .

It is a cyclic number.

It is not a de Polignac number, because 81985650113 - 2²⁰ = 81984601537 is a prime.

It is not a weakly prime, because it can be changed into another prime (81985650143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40992825056 + 40992825057.

It is an arithmetic number, because the mean of its divisors is an integer number (40992825057).

Almost surely, 2^81985650113 is an apocalyptic number.

It is an amenable number.

81985650113 is a deficient number, since it is larger than the sum of its proper divisors (1).

81985650113 is an equidigital number, since it uses as much as digits as its factorization.

81985650113 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 259200, while the sum is 47.

The spelling of 81985650113 in words is "eighty-one billion, nine hundred eighty-five million, six hundred fifty thousand, one hundred thirteen".