81816941 has 2 divisors, whose sum is σ = 81816942. Its totient is φ = 81816940.

The previous prime is 81816913. The next prime is 81816961. The reversal of 81816941 is 14961818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64561225 + 17255716 = 8035^2 + 4154^2 .

It is a cyclic number.

It is not a de Polignac number, because 81816941 - 2¹⁴ = 81800557 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 81816895 and 81816904.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81816901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40908470 + 40908471.

It is an arithmetic number, because the mean of its divisors is an integer number (40908471).

Almost surely, 2^81816941 is an apocalyptic number.

It is an amenable number.

81816941 is a deficient number, since it is larger than the sum of its proper divisors (1).

81816941 is an equidigital number, since it uses as much as digits as its factorization.

81816941 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 38.

The square root of 81816941 is about 9045.2717482672. The cubic root of 81816941 is about 434.1246164691.

The spelling of 81816941 in words is "eighty-one million, eight hundred sixteen thousand, nine hundred forty-one".