81105541 has 4 divisors (see below), whose sum is σ = 88478784. Its totient is φ = 73732300.

The previous prime is 81105523. The next prime is 81105559. The reversal of 81105541 is 14550118.

It is a happy number.

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 an interprime number because it is at equal distance from previous prime (81105523) and next prime (81105559).

It is a cyclic number.

It is not a de Polignac number, because 81105541 - 2⁹ = 81105029 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 (81105581) 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, 3686605 + ... + 3686626.

It is an arithmetic number, because the mean of its divisors is an integer number (22119696).

Almost surely, 2^81105541 is an apocalyptic number.

It is an amenable number.

81105541 is a deficient number, since it is larger than the sum of its proper divisors (7373243).

81105541 is a wasteful number, since it uses less digits than its factorization.

81105541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7373242.

The product of its (nonzero) digits is 800, while the sum is 25.

The square root of 81105541 is about 9005.8614801695. The cubic root of 81105541 is about 432.8627110901.

Adding to 81105541 its reverse (14550118), we get a palindrome (95655659).

The spelling of 81105541 in words is "eighty-one million, one hundred five thousand, five hundred forty-one".