81451823 has 2 divisors, whose sum is σ = 81451824. Its totient is φ = 81451822.

The previous prime is 81451819. The next prime is 81451829. The reversal of 81451823 is 32815418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81451823 - 2² = 81451819 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81451823.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81451829) 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, 40725911 + 40725912.

It is an arithmetic number, because the mean of its divisors is an integer number (40725912).

Almost surely, 2^81451823 is an apocalyptic number.

81451823 is a deficient number, since it is larger than the sum of its proper divisors (1).

81451823 is an equidigital number, since it uses as much as digits as its factorization.

81451823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 32.

The square root of 81451823 is about 9025.0663709471. The cubic root of 81451823 is about 433.4778755814.

The spelling of 81451823 in words is "eighty-one million, four hundred fifty-one thousand, eight hundred twenty-three".