8181993 has 4 divisors (see below), whose sum is σ = 10909328. Its totient is φ = 5454660.

The previous prime is 8181983. The next prime is 8182003. The reversal of 8181993 is 3991818.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (8181983) and next prime (8182003).

It is not a de Polignac number, because 8181993 - 2⁴ = 8181977 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (8181983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1363663 + ... + 1363668.

It is an arithmetic number, because the mean of its divisors is an integer number (2727332).

Almost surely, 2^8181993 is an apocalyptic number.

It is an amenable number.

8181993 is a deficient number, since it is larger than the sum of its proper divisors (2727335).

8181993 is a wasteful number, since it uses less digits than its factorization.

8181993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2727334.

The product of its digits is 15552, while the sum is 39.

The square root of 8181993 is about 2860.4183260495. The cubic root of 8181993 is about 201.5052510089.

The spelling of 8181993 in words is "eight million, one hundred eighty-one thousand, nine hundred ninety-three".