81100643 has 8 divisors (see below), whose sum is σ = 87419136. Its totient is φ = 74793600.

The previous prime is 81100637. The next prime is 81100651. The reversal of 81100643 is 34600118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81100643 - 2²⁰ = 80052067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81100603) 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 7 ways as a sum of consecutive naturals, for example, 17003 + ... + 21243.

It is an arithmetic number, because the mean of its divisors is an integer number (10927392).

Almost surely, 2^81100643 is an apocalyptic number.

81100643 is a deficient number, since it is larger than the sum of its proper divisors (6318493).

81100643 is a wasteful number, since it uses less digits than its factorization.

81100643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5725.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 81100643 is about 9005.5895420566. The cubic root of 81100643 is about 432.8539973236.

The spelling of 81100643 in words is "eighty-one million, one hundred thousand, six hundred forty-three".