81817123 has 4 divisors (see below), whose sum is σ = 82611568. Its totient is φ = 81022680.

The previous prime is 81817121. The next prime is 81817147. The reversal of 81817123 is 32171818.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81817123 - 2¹ = 81817121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81817121) 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, 397068 + ... + 397273.

It is an arithmetic number, because the mean of its divisors is an integer number (20652892).

Almost surely, 2^81817123 is an apocalyptic number.

81817123 is a deficient number, since it is larger than the sum of its proper divisors (794445).

81817123 is a wasteful number, since it uses less digits than its factorization.

81817123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 794444.

The product of its digits is 2688, while the sum is 31.

The square root of 81817123 is about 9045.2818087664. The cubic root of 81817123 is about 434.1249383691.

The spelling of 81817123 in words is "eighty-one million, eight hundred seventeen thousand, one hundred twenty-three".