81239113 has 2 divisors, whose sum is σ = 81239114. Its totient is φ = 81239112.

The previous prime is 81239099. The next prime is 81239143. The reversal of 81239113 is 31193218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54582544 + 26656569 = 7388^2 + 5163^2 .

It is a cyclic number.

It is not a de Polignac number, because 81239113 - 2⁹ = 81238601 is a prime.

It is not a weakly prime, because it can be changed into another prime (81239143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40619556 + 40619557.

It is an arithmetic number, because the mean of its divisors is an integer number (40619557).

Almost surely, 2^81239113 is an apocalyptic number.

It is an amenable number.

81239113 is a deficient number, since it is larger than the sum of its proper divisors (1).

81239113 is an equidigital number, since it uses as much as digits as its factorization.

81239113 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1296, while the sum is 28.

The square root of 81239113 is about 9013.2742663252. The cubic root of 81239113 is about 433.1002066881.

The spelling of 81239113 in words is "eighty-one million, two hundred thirty-nine thousand, one hundred thirteen".