81775537 has 2 divisors, whose sum is σ = 81775538. Its totient is φ = 81775536.

The previous prime is 81775517. The next prime is 81775553. The reversal of 81775537 is 73557718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53056656 + 28718881 = 7284^2 + 5359^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81775537 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81775493 and 81775502.

It is not a weakly prime, because it can be changed into another prime (81775517) 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, 40887768 + 40887769.

It is an arithmetic number, because the mean of its divisors is an integer number (40887769).

Almost surely, 2^81775537 is an apocalyptic number.

It is an amenable number.

81775537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81775537 is an equidigital number, since it uses as much as digits as its factorization.

81775537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 205800, while the sum is 43.

The square root of 81775537 is about 9042.9827490712. The cubic root of 81775537 is about 434.0513735755.

The spelling of 81775537 in words is "eighty-one million, seven hundred seventy-five thousand, five hundred thirty-seven".