81408817 has 4 divisors (see below), whose sum is σ = 93038656. Its totient is φ = 69778980.

The previous prime is 81408809. The next prime is 81408851. The reversal of 81408817 is 71880418.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81408817 - 2³ = 81408809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81408517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5814909 + ... + 5814922.

It is an arithmetic number, because the mean of its divisors is an integer number (23259664).

Almost surely, 2^81408817 is an apocalyptic number.

It is an amenable number.

81408817 is a deficient number, since it is larger than the sum of its proper divisors (11629839).

81408817 is a wasteful number, since it uses less digits than its factorization.

81408817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11629838.

The product of its (nonzero) digits is 14336, while the sum is 37.

The square root of 81408817 is about 9022.6834700105. The cubic root of 81408817 is about 433.4015710422.

The spelling of 81408817 in words is "eighty-one million, four hundred eight thousand, eight hundred seventeen".