81118637 has 2 divisors, whose sum is σ = 81118638. Its totient is φ = 81118636.

The previous prime is 81118633. The next prime is 81118643. The reversal of 81118637 is 73681118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63696361 + 17422276 = 7981^2 + 4174^2 .

It is a cyclic number.

It is not a de Polignac number, because 81118637 - 2² = 81118633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81118597 and 81118606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81118633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40559318 + 40559319.

It is an arithmetic number, because the mean of its divisors is an integer number (40559319).

Almost surely, 2^81118637 is an apocalyptic number.

It is an amenable number.

81118637 is a deficient number, since it is larger than the sum of its proper divisors (1).

81118637 is an equidigital number, since it uses as much as digits as its factorization.

81118637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 35.

The square root of 81118637 is about 9006.5885328464. The cubic root of 81118637 is about 432.8860077515.

The spelling of 81118637 in words is "eighty-one million, one hundred eighteen thousand, six hundred thirty-seven".