81993843 has 8 divisors (see below), whose sum is σ = 121472400. Its totient is φ = 54662544.

The previous prime is 81993841. The next prime is 81993883. The reversal of 81993843 is 34839918.

It is not a de Polignac number, because 81993843 - 2¹ = 81993841 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81993841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1518378 + ... + 1518431.

It is an arithmetic number, because the mean of its divisors is an integer number (15184050).

Almost surely, 2^81993843 is an apocalyptic number.

81993843 is a deficient number, since it is larger than the sum of its proper divisors (39478557).

81993843 is a wasteful number, since it uses less digits than its factorization.

81993843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3036818 (or 3036812 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 81993843 is about 9055.0451683026. The cubic root of 81993843 is about 434.4372747386.

The spelling of 81993843 in words is "eighty-one million, nine hundred ninety-three thousand, eight hundred forty-three".