81575591 has 2 divisors, whose sum is σ = 81575592. Its totient is φ = 81575590.

The previous prime is 81575587. The next prime is 81575617. The reversal of 81575591 is 19557518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81575591 - 2² = 81575587 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81575561) 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, 40787795 + 40787796.

It is an arithmetic number, because the mean of its divisors is an integer number (40787796).

Almost surely, 2^81575591 is an apocalyptic number.

81575591 is a deficient number, since it is larger than the sum of its proper divisors (1).

81575591 is an equidigital number, since it uses as much as digits as its factorization.

81575591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63000, while the sum is 41.

The square root of 81575591 is about 9031.9206705994. The cubic root of 81575591 is about 433.6973244783.

The spelling of 81575591 in words is "eighty-one million, five hundred seventy-five thousand, five hundred ninety-one".