81812623 has 2 divisors, whose sum is σ = 81812624. Its totient is φ = 81812622.

The previous prime is 81812603. The next prime is 81812639. The reversal of 81812623 is 32621818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81812623 - 2⁹ = 81812111 is a prime.

It is equal to p_4769104 and since 81812623 and 4769104 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81812603) 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, 40906311 + 40906312.

It is an arithmetic number, because the mean of its divisors is an integer number (40906312).

Almost surely, 2^81812623 is an apocalyptic number.

81812623 is a deficient number, since it is larger than the sum of its proper divisors (1).

81812623 is an equidigital number, since it uses as much as digits as its factorization.

81812623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4608, while the sum is 31.

The square root of 81812623 is about 9045.0330568771. The cubic root of 81812623 is about 434.1169791630.

The spelling of 81812623 in words is "eighty-one million, eight hundred twelve thousand, six hundred twenty-three".