81381009 has 8 divisors (see below), whose sum is σ = 114219040. Its totient is φ = 51398496.

The previous prime is 81380953. The next prime is 81381011. The reversal of 81381009 is 90018318.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81381009 - 2⁷ = 81380881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81381059) 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 7 ways as a sum of consecutive naturals, for example, 713812 + ... + 713925.

It is an arithmetic number, because the mean of its divisors is an integer number (14277380).

Almost surely, 2^81381009 is an apocalyptic number.

It is an amenable number.

81381009 is a deficient number, since it is larger than the sum of its proper divisors (32838031).

81381009 is a wasteful number, since it uses less digits than its factorization.

81381009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1427759.

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 81381009 is about 9021.1423334298. The cubic root of 81381009 is about 433.3522176517.

The spelling of 81381009 in words is "eighty-one million, three hundred eighty-one thousand, nine".