81103681 has 4 divisors (see below), whose sum is σ = 84629952. Its totient is φ = 77577412.

The previous prime is 81103619. The next prime is 81103721. The reversal of 81103681 is 18630118.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81103681 is a prime.

It is a super-2 number, since 2×81103681² = 13155614143499522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81103601) 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, 1763101 + ... + 1763146.

It is an arithmetic number, because the mean of its divisors is an integer number (21157488).

Almost surely, 2^81103681 is an apocalyptic number.

It is an amenable number.

81103681 is a deficient number, since it is larger than the sum of its proper divisors (3526271).

81103681 is a wasteful number, since it uses less digits than its factorization.

81103681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3526270.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 81103681 is about 9005.7582134987. The cubic root of 81103681 is about 432.8594021062.

Adding to 81103681 its reverse (18630118), we get a palindrome (99733799).

The spelling of 81103681 in words is "eighty-one million, one hundred three thousand, six hundred eighty-one".