81582791 has 2 divisors, whose sum is σ = 81582792. Its totient is φ = 81582790.

The previous prime is 81582757. The next prime is 81582797. The reversal of 81582791 is 19728518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81582791 - 2¹⁰ = 81581767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81582797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40791395 + 40791396.

It is an arithmetic number, because the mean of its divisors is an integer number (40791396).

Almost surely, 2^81582791 is an apocalyptic number.

81582791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81582791 is an equidigital number, since it uses as much as digits as its factorization.

81582791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 41.

The square root of 81582791 is about 9032.3192481223. The cubic root of 81582791 is about 433.7100837233.

The spelling of 81582791 in words is "eighty-one million, five hundred eighty-two thousand, seven hundred ninety-one".