81218171659 has 2 divisors, whose sum is σ = 81218171660. Its totient is φ = 81218171658.

The previous prime is 81218171611. The next prime is 81218171689. The reversal of 81218171659 is 95617181218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81218171659 - 2⁹ = 81218171147 is a prime.

It is not a weakly prime, because it can be changed into another prime (81218171689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40609085829 + 40609085830.

It is an arithmetic number, because the mean of its divisors is an integer number (40609085830).

Almost surely, 2^81218171659 is an apocalyptic number.

81218171659 is a deficient number, since it is larger than the sum of its proper divisors (1).

81218171659 is an equidigital number, since it uses as much as digits as its factorization.

81218171659 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 49.

The spelling of 81218171659 in words is "eighty-one billion, two hundred eighteen million, one hundred seventy-one thousand, six hundred fifty-nine".