81100645 has 16 divisors (see below), whose sum is σ = 106899840. Its totient is φ = 58791744.

The previous prime is 81100637. The next prime is 81100651. The reversal of 81100645 is 54600118.

It is a cyclic number.

It is not a de Polignac number, because 81100645 - 2³ = 81100637 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 16374 + ... + 20743.

It is an arithmetic number, because the mean of its divisors is an integer number (6681240).

Almost surely, 2^81100645 is an apocalyptic number.

It is an amenable number.

81100645 is a deficient number, since it is larger than the sum of its proper divisors (25799195).

81100645 is a wasteful number, since it uses less digits than its factorization.

81100645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37164.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 81100645 is about 9005.5896530988. The cubic root of 81100645 is about 432.8540008818.

The spelling of 81100645 in words is "eighty-one million, one hundred thousand, six hundred forty-five".