81009381 has 8 divisors (see below), whose sum is σ = 112708800. Its totient is φ = 51658112.

The previous prime is 81009371. The next prime is 81009389. The reversal of 81009381 is 18390018.

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

It is a cyclic number.

It is not a de Polignac number, because 81009381 - 2⁵ = 81009349 is a prime.

It is a super-2 number, since 2×81009381² = 13125039620006322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81009389) 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, 586956 + ... + 587093.

It is an arithmetic number, because the mean of its divisors is an integer number (14088600).

Almost surely, 2^81009381 is an apocalyptic number.

It is an amenable number.

81009381 is a deficient number, since it is larger than the sum of its proper divisors (31699419).

81009381 is a wasteful number, since it uses less digits than its factorization.

81009381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1174075.

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

The square root of 81009381 is about 9000.5211515778. The cubic root of 81009381 is about 432.6915738341.

Adding to 81009381 its reverse (18390018), we get a palindrome (99399399).

The spelling of 81009381 in words is "eighty-one million, nine thousand, three hundred eighty-one".