18098921 has 4 divisors (see below), whose sum is σ = 18114372. Its totient is φ = 18083472.

The previous prime is 18098909. The next prime is 18098923. The reversal of 18098921 is 12989081.

18098921 is nontrivially palindromic in base 5.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13957696 + 4141225 = 3736^2 + 2035^2 .

It is a cyclic number.

It is not a de Polignac number, because 18098921 - 2¹⁰ = 18097897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18098923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5810 + ... + 8363.

It is an arithmetic number, because the mean of its divisors is an integer number (4528593).

Almost surely, 2^18098921 is an apocalyptic number.

It is an amenable number.

18098921 is a deficient number, since it is larger than the sum of its proper divisors (15451).

18098921 is a wasteful number, since it uses less digits than its factorization.

18098921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15450.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 18098921 is about 4254.2826657381. The cubic root of 18098921 is about 262.5533484920.

The spelling of 18098921 in words is "eighteen million, ninety-eight thousand, nine hundred twenty-one".