81232909 has 2 divisors, whose sum is σ = 81232910. Its totient is φ = 81232908.

The previous prime is 81232903. The next prime is 81232937. The reversal of 81232909 is 90923218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81090025 + 142884 = 9005^2 + 378^2 .

It is a cyclic number.

It is not a de Polignac number, because 81232909 - 2³ = 81232901 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81232901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40616454 + 40616455.

It is an arithmetic number, because the mean of its divisors is an integer number (40616455).

Almost surely, 2^81232909 is an apocalyptic number.

It is an amenable number.

81232909 is a deficient number, since it is larger than the sum of its proper divisors (1).

81232909 is an equidigital number, since it uses as much as digits as its factorization.

81232909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 81232909 is about 9012.9301006942. The cubic root of 81232909 is about 433.0891815305.

The spelling of 81232909 in words is "eighty-one million, two hundred thirty-two thousand, nine hundred nine".