81560549173 has 2 divisors, whose sum is σ = 81560549174. Its totient is φ = 81560549172.

The previous prime is 81560549129. The next prime is 81560549227. The reversal of 81560549173 is 37194506518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55085028804 + 26475520369 = 234702^2 + 162713^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81560549173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81560349173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40780274586 + 40780274587.

It is an arithmetic number, because the mean of its divisors is an integer number (40780274587).

Almost surely, 2^81560549173 is an apocalyptic number.

It is an amenable number.

81560549173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81560549173 is an equidigital number, since it uses as much as digits as its factorization.

81560549173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 907200, while the sum is 49.

The spelling of 81560549173 in words is "eighty-one billion, five hundred sixty million, five hundred forty-nine thousand, one hundred seventy-three".