81571433 has 2 divisors, whose sum is σ = 81571434. Its totient is φ = 81571432.

The previous prime is 81571331. The next prime is 81571463. The reversal of 81571433 is 33417518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69089344 + 12482089 = 8312^2 + 3533^2 .

It is a cyclic number.

It is not a de Polignac number, because 81571433 - 2²⁰ = 80522857 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81571433.

It is not a weakly prime, because it can be changed into another prime (81571463) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40785716 + 40785717.

It is an arithmetic number, because the mean of its divisors is an integer number (40785717).

Almost surely, 2^81571433 is an apocalyptic number.

It is an amenable number.

81571433 is a deficient number, since it is larger than the sum of its proper divisors (1).

81571433 is an equidigital number, since it uses as much as digits as its factorization.

81571433 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 32.

The square root of 81571433 is about 9031.6904840678. The cubic root of 81571433 is about 433.6899556723.

The spelling of 81571433 in words is "eighty-one million, five hundred seventy-one thousand, four hundred thirty-three".