20181993 has 8 divisors (see below), whose sum is σ = 28979328. Its totient is φ = 12419664.

The previous prime is 20181989. The next prime is 20182013. The reversal of 20181993 is 39918102.

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

It is not a de Polignac number, because 20181993 - 2² = 20181989 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20181793) 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, 258705 + ... + 258782.

It is an arithmetic number, because the mean of its divisors is an integer number (3622416).

Almost surely, 2^20181993 is an apocalyptic number.

It is an amenable number.

20181993 is a deficient number, since it is larger than the sum of its proper divisors (8797335).

20181993 is a wasteful number, since it uses less digits than its factorization.

20181993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 517503.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 20181993 is about 4492.4373117496. The cubic root of 20181993 is about 272.2626185103.

The spelling of 20181993 in words is "twenty million, one hundred eighty-one thousand, nine hundred ninety-three".