81108187513 has 2 divisors, whose sum is σ = 81108187514. Its totient is φ = 81108187512.

The previous prime is 81108187483. The next prime is 81108187547. The reversal of 81108187513 is 31578180118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64522096144 + 16586091369 = 254012^2 + 128787^2 .

It is a cyclic number.

It is not a de Polignac number, because 81108187513 - 2¹⁷ = 81108056441 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81108187513.

It is not a weakly prime, because it can be changed into another prime (81108187213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40554093756 + 40554093757.

It is an arithmetic number, because the mean of its divisors is an integer number (40554093757).

Almost surely, 2^81108187513 is an apocalyptic number.

It is an amenable number.

81108187513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81108187513 is an equidigital number, since it uses as much as digits as its factorization.

81108187513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 53760, while the sum is 43.

The spelling of 81108187513 in words is "eighty-one billion, one hundred eight million, one hundred eighty-seven thousand, five hundred thirteen".