81766556941 has 2 divisors, whose sum is σ = 81766556942. Its totient is φ = 81766556940.

The previous prime is 81766556863. The next prime is 81766556953. The reversal of 81766556941 is 14965566718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42817955625 + 38948601316 = 206925^2 + 197354^2 .

It is a cyclic number.

It is not a de Polignac number, because 81766556941 - 2⁷ = 81766556813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81766556141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40883278470 + 40883278471.

It is an arithmetic number, because the mean of its divisors is an integer number (40883278471).

Almost surely, 2^81766556941 is an apocalyptic number.

It is an amenable number.

81766556941 is a deficient number, since it is larger than the sum of its proper divisors (1).

81766556941 is an equidigital number, since it uses as much as digits as its factorization.

81766556941 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10886400, while the sum is 58.

The spelling of 81766556941 in words is "eighty-one billion, seven hundred sixty-six million, five hundred fifty-six thousand, nine hundred forty-one".