81566941 has 2 divisors, whose sum is σ = 81566942. Its totient is φ = 81566940.

The previous prime is 81566909. The next prime is 81566951. The reversal of 81566941 is 14966518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81522841 + 44100 = 9029^2 + 210^2 .

It is a cyclic number.

It is not a de Polignac number, because 81566941 - 2⁵ = 81566909 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81566894 and 81566903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81566951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40783470 + 40783471.

It is an arithmetic number, because the mean of its divisors is an integer number (40783471).

Almost surely, 2^81566941 is an apocalyptic number.

It is an amenable number.

81566941 is a deficient number, since it is larger than the sum of its proper divisors (1).

81566941 is an equidigital number, since it uses as much as digits as its factorization.

81566941 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 40.

The square root of 81566941 is about 9031.4418007315. The cubic root of 81566941 is about 433.6819946702.

The spelling of 81566941 in words is "eighty-one million, five hundred sixty-six thousand, nine hundred forty-one".