17921993 has 4 divisors (see below), whose sum is σ = 18303360. Its totient is φ = 17540628.

The previous prime is 17921989. The next prime is 17922001. The reversal of 17921993 is 39912971.

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 a cyclic number.

It is not a de Polignac number, because 17921993 - 2² = 17921989 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 17921993.

It is not an unprimeable number, because it can be changed into a prime (17921923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 190613 + ... + 190706.

It is an arithmetic number, because the mean of its divisors is an integer number (4575840).

Almost surely, 2^17921993 is an apocalyptic number.

It is an amenable number.

17921993 is a deficient number, since it is larger than the sum of its proper divisors (381367).

17921993 is an equidigital number, since it uses as much as digits as its factorization.

17921993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 381366.

The product of its digits is 30618, while the sum is 41.

The square root of 17921993 is about 4233.4374921569. The cubic root of 17921993 is about 261.6950056983.

The spelling of 17921993 in words is "seventeen million, nine hundred twenty-one thousand, nine hundred ninety-three".