81106861 has 4 divisors (see below), whose sum is σ = 88480224. Its totient is φ = 73733500.

The previous prime is 81106859. The next prime is 81106867. The reversal of 81106861 is 16860118.

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 not a de Polignac number, because 81106861 - 2¹ = 81106859 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81106867) 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, 3686665 + ... + 3686686.

It is an arithmetic number, because the mean of its divisors is an integer number (22120056).

Almost surely, 2^81106861 is an apocalyptic number.

It is an amenable number.

81106861 is a deficient number, since it is larger than the sum of its proper divisors (7373363).

81106861 is a wasteful number, since it uses less digits than its factorization.

81106861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7373362.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 81106861 is about 9005.9347654755. The cubic root of 81106861 is about 432.8650593706.

Adding to 81106861 its reverse (16860118), we get a palindrome (97966979).

The spelling of 81106861 in words is "eighty-one million, one hundred six thousand, eight hundred sixty-one".