81266573 has 2 divisors, whose sum is σ = 81266574. Its totient is φ = 81266572.

The previous prime is 81266561. The next prime is 81266587. The reversal of 81266573 is 37566218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69522244 + 11744329 = 8338^2 + 3427^2 .

It is a cyclic number.

It is not a de Polignac number, because 81266573 - 2⁶ = 81266509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81266533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40633286 + 40633287.

It is an arithmetic number, because the mean of its divisors is an integer number (40633287).

Almost surely, 2^81266573 is an apocalyptic number.

It is an amenable number.

81266573 is a deficient number, since it is larger than the sum of its proper divisors (1).

81266573 is an equidigital number, since it uses as much as digits as its factorization.

81266573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 38.

The square root of 81266573 is about 9014.7974464211. The cubic root of 81266573 is about 433.1489992442.

The spelling of 81266573 in words is "eighty-one million, two hundred sixty-six thousand, five hundred seventy-three".