18538993 has 8 divisors (see below), whose sum is σ = 21414240. Its totient is φ = 15862080.

The previous prime is 18538981. The next prime is 18538997. The reversal of 18538993 is 39983581.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18538993 is a prime.

It is a super-2 number, since 2×18538993² = 687388522908098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18538997) 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 7 ways as a sum of consecutive naturals, for example, 49383 + ... + 49756.

It is an arithmetic number, because the mean of its divisors is an integer number (2676780).

Almost surely, 2^18538993 is an apocalyptic number.

It is an amenable number.

18538993 is a deficient number, since it is larger than the sum of its proper divisors (2875247).

18538993 is a wasteful number, since it uses less digits than its factorization.

18538993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99167.

The product of its digits is 233280, while the sum is 46.

The square root of 18538993 is about 4305.6930917101. The cubic root of 18538993 is about 264.6643097230.

The spelling of 18538993 in words is "eighteen million, five hundred thirty-eight thousand, nine hundred ninety-three".