81813653 has 2 divisors, whose sum is σ = 81813654. Its totient is φ = 81813652.

The previous prime is 81813647. The next prime is 81813659. The reversal of 81813653 is 35631818.

It is a balanced prime because it is at equal distance from previous prime (81813647) and next prime (81813659).

It can be written as a sum of positive squares in only one way, i.e., 80694289 + 1119364 = 8983^2 + 1058^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81813653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81813659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40906826 + 40906827.

It is an arithmetic number, because the mean of its divisors is an integer number (40906827).

Almost surely, 2^81813653 is an apocalyptic number.

It is an amenable number.

81813653 is a deficient number, since it is larger than the sum of its proper divisors (1).

81813653 is an equidigital number, since it uses as much as digits as its factorization.

81813653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 35.

The square root of 81813653 is about 9045.0899940244. The cubic root of 81813653 is about 434.1188009626.

The spelling of 81813653 in words is "eighty-one million, eight hundred thirteen thousand, six hundred fifty-three".