81155442373 has 2 divisors, whose sum is σ = 81155442374. Its totient is φ = 81155442372.

The previous prime is 81155442223. The next prime is 81155442413. The reversal of 81155442373 is 37324455118.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53646897924 + 27508544449 = 231618^2 + 165857^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81155442373 is a prime.

It is a super-2 number, since 2×81155442373² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81155442073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40577721186 + 40577721187.

It is an arithmetic number, because the mean of its divisors is an integer number (40577721187).

Almost surely, 2^81155442373 is an apocalyptic number.

It is an amenable number.

81155442373 is a deficient number, since it is larger than the sum of its proper divisors (1).

81155442373 is an equidigital number, since it uses as much as digits as its factorization.

81155442373 is an evil number, because the sum of its binary digits is even.

The product of its digits is 403200, while the sum is 43.

The spelling of 81155442373 in words is "eighty-one billion, one hundred fifty-five million, four hundred forty-two thousand, three hundred seventy-three".