18161998 has 8 divisors (see below), whose sum is σ = 27271008. Its totient is φ = 9071664.

The previous prime is 18161993. The next prime is 18162007. The reversal of 18161998 is 89916181.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18161993) 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, 1911 + ... + 6322.

It is an arithmetic number, because the mean of its divisors is an integer number (3408876).

Almost surely, 2^18161998 is an apocalyptic number.

18161998 is a deficient number, since it is larger than the sum of its proper divisors (9109010).

18161998 is a wasteful number, since it uses less digits than its factorization.

18161998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9338.

The product of its digits is 31104, while the sum is 43.

The square root of 18161998 is about 4261.6895710504. The cubic root of 18161998 is about 262.8580052463.

The spelling of 18161998 in words is "eighteen million, one hundred sixty-one thousand, nine hundred ninety-eight".