81645093 has 6 divisors (see below), whose sum is σ = 117931814. Its totient is φ = 54430056.

The previous prime is 81645079. The next prime is 81645097. The reversal of 81645093 is 39054618.

81645093 is a `hidden beast` number, since 8 + 1 + 645 + 0 + 9 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 74338884 + 7306209 = 8622^2 + 2703^2 .

It is not a de Polignac number, because 81645093 - 2⁴ = 81645077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81645097) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4535830 + ... + 4535847.

Almost surely, 2^81645093 is an apocalyptic number.

It is an amenable number.

81645093 is a deficient number, since it is larger than the sum of its proper divisors (36286721).

81645093 is a wasteful number, since it uses less digits than its factorization.

81645093 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9071683 (or 9071680 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 81645093 is about 9035.7674272859. The cubic root of 81645093 is about 433.8204588400.

The spelling of 81645093 in words is "eighty-one million, six hundred forty-five thousand, ninety-three".