81412109 has 2 divisors, whose sum is σ = 81412110. Its totient is φ = 81412108.

The previous prime is 81412091. The next prime is 81412129. The reversal of 81412109 is 90121418.

Together with previous prime (81412091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81396484 + 15625 = 9022^2 + 125^2 .

It is a cyclic number.

It is not a de Polignac number, because 81412109 - 2¹² = 81408013 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 (81412129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40706054 + 40706055.

It is an arithmetic number, because the mean of its divisors is an integer number (40706055).

Almost surely, 2^81412109 is an apocalyptic number.

It is an amenable number.

81412109 is a deficient number, since it is larger than the sum of its proper divisors (1).

81412109 is an equidigital number, since it uses as much as digits as its factorization.

81412109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 81412109 is about 9022.8658972635. The cubic root of 81412109 is about 433.4074129104.

The spelling of 81412109 in words is "eighty-one million, four hundred twelve thousand, one hundred nine".