81813293 has 2 divisors, whose sum is σ = 81813294. Its totient is φ = 81813292.

The previous prime is 81813289. The next prime is 81813331. The reversal of 81813293 is 39231818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81667369 + 145924 = 9037^2 + 382^2 .

It is a cyclic number.

It is not a de Polignac number, because 81813293 - 2² = 81813289 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81813233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40906646 + 40906647.

It is an arithmetic number, because the mean of its divisors is an integer number (40906647).

Almost surely, 2^81813293 is an apocalyptic number.

It is an amenable number.

81813293 is a deficient number, since it is larger than the sum of its proper divisors (1).

81813293 is an equidigital number, since it uses as much as digits as its factorization.

81813293 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 35.

The square root of 81813293 is about 9045.0700937030. The cubic root of 81813293 is about 434.1181642188.

The spelling of 81813293 in words is "eighty-one million, eight hundred thirteen thousand, two hundred ninety-three".