81755893 has 2 divisors, whose sum is σ = 81755894. Its totient is φ = 81755892.

The previous prime is 81755851. The next prime is 81755909. The reversal of 81755893 is 39855718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61748164 + 20007729 = 7858^2 + 4473^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81755893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81755813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40877946 + 40877947.

It is an arithmetic number, because the mean of its divisors is an integer number (40877947).

Almost surely, 2^81755893 is an apocalyptic number.

It is an amenable number.

81755893 is a deficient number, since it is larger than the sum of its proper divisors (1).

81755893 is an equidigital number, since it uses as much as digits as its factorization.

81755893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 302400, while the sum is 46.

The square root of 81755893 is about 9041.8965377845. The cubic root of 81755893 is about 434.0166150633.

The spelling of 81755893 in words is "eighty-one million, seven hundred fifty-five thousand, eight hundred ninety-three".