81566190606233 has 2 divisors, whose sum is σ = 81566190606234. Its totient is φ = 81566190606232.

The previous prime is 81566190606211. The next prime is 81566190606301. The reversal of 81566190606233 is 33260609166518.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73325174512144 + 8241016094089 = 8563012^2 + 2870717^2 .

It is a cyclic number.

It is not a de Polignac number, because 81566190606233 - 2¹⁶ = 81566190540697 is a prime.

It is not a weakly prime, because it can be changed into another prime (81566190606203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40783095303116 + 40783095303117.

It is an arithmetic number, because the mean of its divisors is an integer number (40783095303117).

Almost surely, 2^{81566190606233} is an apocalyptic number.

It is an amenable number.

81566190606233 is a deficient number, since it is larger than the sum of its proper divisors (1).

81566190606233 is an equidigital number, since it uses as much as digits as its factorization.

81566190606233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8398080, while the sum is 56.

The spelling of 81566190606233 in words is "eighty-one trillion, five hundred sixty-six billion, one hundred ninety million, six hundred six thousand, two hundred thirty-three".