81318959 has 2 divisors, whose sum is σ = 81318960. Its totient is φ = 81318958.

The previous prime is 81318947. The next prime is 81318997. The reversal of 81318959 is 95981318.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81318959 is a prime.

It is a super-2 number, since 2×81318959² = 13225546185687362, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81318659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40659479 + 40659480.

It is an arithmetic number, because the mean of its divisors is an integer number (40659480).

Almost surely, 2^81318959 is an apocalyptic number.

81318959 is a deficient number, since it is larger than the sum of its proper divisors (1).

81318959 is an equidigital number, since it uses as much as digits as its factorization.

81318959 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 44.

The square root of 81318959 is about 9017.7025344597. The cubic root of 81318959 is about 433.2420513184.

The spelling of 81318959 in words is "eighty-one million, three hundred eighteen thousand, nine hundred fifty-nine".