81100123 has 16 divisors (see below), whose sum is σ = 91881216. Its totient is φ = 71061120.

The previous prime is 81100087. The next prime is 81100141. The reversal of 81100123 is 32100118.

It is not a de Polignac number, because 81100123 - 2²¹ = 79002971 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81100097 and 81100106.

It is not an unprimeable number, because it can be changed into a prime (81100163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19461 + ... + 23257.

It is an arithmetic number, because the mean of its divisors is an integer number (5742576).

Almost surely, 2^81100123 is an apocalyptic number.

81100123 is a deficient number, since it is larger than the sum of its proper divisors (10781093).

81100123 is a wasteful number, since it uses less digits than its factorization.

81100123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3894.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 81100123 is about 9005.5606710521. The cubic root of 81100123 is about 432.8530721992.

The spelling of 81100123 in words is "eighty-one million, one hundred thousand, one hundred twenty-three".