81253729 has 2 divisors, whose sum is σ = 81253730. Its totient is φ = 81253728.

The previous prime is 81253681. The next prime is 81253771. The reversal of 81253729 is 92735218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73702225 + 7551504 = 8585^2 + 2748^2 .

It is a cyclic number.

It is not a de Polignac number, because 81253729 - 2²¹ = 79156577 is a prime.

It is not a weakly prime, because it can be changed into another prime (81253129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40626864 + 40626865.

It is an arithmetic number, because the mean of its divisors is an integer number (40626865).

Almost surely, 2^81253729 is an apocalyptic number.

It is an amenable number.

81253729 is a deficient number, since it is larger than the sum of its proper divisors (1).

81253729 is an equidigital number, since it uses as much as digits as its factorization.

81253729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 37.

The square root of 81253729 is about 9014.0850339899. The cubic root of 81253729 is about 433.1261786319.

The spelling of 81253729 in words is "eighty-one million, two hundred fifty-three thousand, seven hundred twenty-nine".