81718640623 has 2 divisors, whose sum is σ = 81718640624. Its totient is φ = 81718640622.

The previous prime is 81718640621. The next prime is 81718640659. The reversal of 81718640623 is 32604681718.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81718640623 - 2¹ = 81718640621 is a prime.

Together with 81718640621, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81718640621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40859320311 + 40859320312.

It is an arithmetic number, because the mean of its divisors is an integer number (40859320312).

Almost surely, 2^81718640623 is an apocalyptic number.

81718640623 is a deficient number, since it is larger than the sum of its proper divisors (1).

81718640623 is an equidigital number, since it uses as much as digits as its factorization.

81718640623 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 387072, while the sum is 46.

The spelling of 81718640623 in words is "eighty-one billion, seven hundred eighteen million, six hundred forty thousand, six hundred twenty-three".