81373861 has 2 divisors, whose sum is σ = 81373862. Its totient is φ = 81373860.

The previous prime is 81373847. The next prime is 81373909. The reversal of 81373861 is 16837318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65124900 + 16248961 = 8070^2 + 4031^2 .

It is a cyclic number.

It is not a de Polignac number, because 81373861 - 2⁵ = 81373829 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81373861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81373261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40686930 + 40686931.

It is an arithmetic number, because the mean of its divisors is an integer number (40686931).

Almost surely, 2^81373861 is an apocalyptic number.

It is an amenable number.

81373861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81373861 is an equidigital number, since it uses as much as digits as its factorization.

81373861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 37.

The square root of 81373861 is about 9020.7461443054. The cubic root of 81373861 is about 433.3395296287.

The spelling of 81373861 in words is "eighty-one million, three hundred seventy-three thousand, eight hundred sixty-one".