81751157 has 2 divisors, whose sum is σ = 81751158. Its totient is φ = 81751156.

The previous prime is 81751139. The next prime is 81751169. The reversal of 81751157 is 75115718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56761156 + 24990001 = 7534^2 + 4999^2 .

It is a cyclic number.

It is not a de Polignac number, because 81751157 - 2¹⁰ = 81750133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81759157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40875578 + 40875579.

It is an arithmetic number, because the mean of its divisors is an integer number (40875579).

Almost surely, 2^81751157 is an apocalyptic number.

It is an amenable number.

81751157 is a deficient number, since it is larger than the sum of its proper divisors (1).

81751157 is an equidigital number, since it uses as much as digits as its factorization.

81751157 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9800, while the sum is 35.

The square root of 81751157 is about 9041.6346420324. The cubic root of 81751157 is about 434.0082342510.

The spelling of 81751157 in words is "eighty-one million, seven hundred fifty-one thousand, one hundred fifty-seven".