18321998 has 8 divisors (see below), whose sum is σ = 28153440. Its totient is φ = 8937520.

The previous prime is 18321991. The next prime is 18322013. The reversal of 18321998 is 89912381.

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

It is a super-2 number, since 2×18321998² = 671391221424008, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18321991) 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, 111638 + ... + 111801.

It is an arithmetic number, because the mean of its divisors is an integer number (3519180).

Almost surely, 2^18321998 is an apocalyptic number.

18321998 is a deficient number, since it is larger than the sum of its proper divisors (9831442).

18321998 is a wasteful number, since it uses less digits than its factorization.

18321998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223482.

The product of its digits is 31104, while the sum is 41.

The square root of 18321998 is about 4280.4203064652. The cubic root of 18321998 is about 263.6276411844.

The spelling of 18321998 in words is "eighteen million, three hundred twenty-one thousand, nine hundred ninety-eight".