81189950568413 has 2 divisors, whose sum is σ = 81189950568414. Its totient is φ = 81189950568412.

The previous prime is 81189950568401. The next prime is 81189950568443. The reversal of 81189950568413 is 31486505998118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51604640547769 + 29585310020644 = 7183637^2 + 5439238^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81189950568413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81189950568443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40594975284206 + 40594975284207.

It is an arithmetic number, because the mean of its divisors is an integer number (40594975284207).

Almost surely, 2^{81189950568413} is an apocalyptic number.

It is an amenable number.

81189950568413 is a deficient number, since it is larger than the sum of its proper divisors (1).

81189950568413 is an equidigital number, since it uses as much as digits as its factorization.

81189950568413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 74649600, while the sum is 68.

The spelling of 81189950568413 in words is "eighty-one trillion, one hundred eighty-nine billion, nine hundred fifty million, five hundred sixty-eight thousand, four hundred thirteen".