81847009 has 2 divisors, whose sum is σ = 81847010. Its totient is φ = 81847008.

The previous prime is 81847001. The next prime is 81847033. The reversal of 81847009 is 90074818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81504784 + 342225 = 9028^2 + 585^2 .

It is a cyclic number.

It is not a de Polignac number, because 81847009 - 2³ = 81847001 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81847001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40923504 + 40923505.

It is an arithmetic number, because the mean of its divisors is an integer number (40923505).

Almost surely, 2^81847009 is an apocalyptic number.

It is an amenable number.

81847009 is a deficient number, since it is larger than the sum of its proper divisors (1).

81847009 is an equidigital number, since it uses as much as digits as its factorization.

81847009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 81847009 is about 9046.9336794297. The cubic root of 81847009 is about 434.1777907062.

The spelling of 81847009 in words is "eighty-one million, eight hundred forty-seven thousand, nine".