81290791 has 2 divisors, whose sum is σ = 81290792. Its totient is φ = 81290790.

The previous prime is 81290779. The next prime is 81290819. The reversal of 81290791 is 19709218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81290791 - 2⁷ = 81290663 is a prime.

It is a super-3 number, since 3×81290791³ (a number of 25 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81290791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81290701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40645395 + 40645396.

It is an arithmetic number, because the mean of its divisors is an integer number (40645396).

Almost surely, 2^81290791 is an apocalyptic number.

81290791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81290791 is an equidigital number, since it uses as much as digits as its factorization.

81290791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 81290791 is about 9016.1405823113. The cubic root of 81290791 is about 433.1920221018.

The spelling of 81290791 in words is "eighty-one million, two hundred ninety thousand, seven hundred ninety-one".