81343609 has 2 divisors, whose sum is σ = 81343610. Its totient is φ = 81343608.

The previous prime is 81343607. The next prime is 81343621. The reversal of 81343609 is 90634318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69973225 + 11370384 = 8365^2 + 3372^2 .

It is a cyclic number.

It is not a de Polignac number, because 81343609 - 2¹ = 81343607 is a prime.

Together with 81343607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81343607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40671804 + 40671805.

It is an arithmetic number, because the mean of its divisors is an integer number (40671805).

Almost surely, 2^81343609 is an apocalyptic number.

It is an amenable number.

81343609 is a deficient number, since it is larger than the sum of its proper divisors (1).

81343609 is an equidigital number, since it uses as much as digits as its factorization.

81343609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 34.

The square root of 81343609 is about 9019.0691870059. The cubic root of 81343609 is about 433.2858227333.

The spelling of 81343609 in words is "eighty-one million, three hundred forty-three thousand, six hundred nine".