81138589 has 4 divisors (see below), whose sum is σ = 92729824. Its totient is φ = 69547356.

The previous prime is 81138527. The next prime is 81138599. The reversal of 81138589 is 98583118.

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, and also an emirpimes, since its reverse is a distinct semiprime: 98583118 = 2 ⋅49291559.

It is a cyclic number.

It is not a de Polignac number, because 81138589 - 2⁷ = 81138461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81138509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5795607 + ... + 5795620.

It is an arithmetic number, because the mean of its divisors is an integer number (23182456).

Almost surely, 2^81138589 is an apocalyptic number.

It is an amenable number.

81138589 is a deficient number, since it is larger than the sum of its proper divisors (11591235).

81138589 is a wasteful number, since it uses less digits than its factorization.

81138589 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11591234.

The product of its digits is 69120, while the sum is 43.

The square root of 81138589 is about 9007.6960983372. The cubic root of 81138589 is about 432.9214958297.

The spelling of 81138589 in words is "eighty-one million, one hundred thirty-eight thousand, five hundred eighty-nine".