81742109 has 2 divisors, whose sum is σ = 81742110. Its totient is φ = 81742108.

The previous prime is 81742099. The next prime is 81742121. The reversal of 81742109 is 90124718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71995225 + 9746884 = 8485^2 + 3122^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81742109 is a prime.

It is equal to p_4765262 and since 81742109 and 4765262 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 (81742709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40871054 + 40871055.

It is an arithmetic number, because the mean of its divisors is an integer number (40871055).

Almost surely, 2^81742109 is an apocalyptic number.

It is an amenable number.

81742109 is a deficient number, since it is larger than the sum of its proper divisors (1).

81742109 is an equidigital number, since it uses as much as digits as its factorization.

81742109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 81742109 is about 9041.1342761846. The cubic root of 81742109 is about 433.9922220356.

The spelling of 81742109 in words is "eighty-one million, seven hundred forty-two thousand, one hundred nine".