81548591 has 2 divisors, whose sum is σ = 81548592. Its totient is φ = 81548590.

The previous prime is 81548587. The next prime is 81548603. The reversal of 81548591 is 19584518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81548591 - 2² = 81548587 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81548491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40774295 + 40774296.

It is an arithmetic number, because the mean of its divisors is an integer number (40774296).

Almost surely, 2^81548591 is an apocalyptic number.

81548591 is a deficient number, since it is larger than the sum of its proper divisors (1).

81548591 is an equidigital number, since it uses as much as digits as its factorization.

81548591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57600, while the sum is 41.

The square root of 81548591 is about 9030.4258482089. The cubic root of 81548591 is about 433.6494706216.

The spelling of 81548591 in words is "eighty-one million, five hundred forty-eight thousand, five hundred ninety-one".