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18990 = 2325211
BaseRepresentation
bin100101000101110
3222001100
410220232
51101430
6223530
7106236
oct45056
928040
1018990
11132a4
12aba6
13884a
146cc6
155960
hex4a2e

18990 has 24 divisors (see below), whose sum is σ = 49608. Its totient is φ = 5040.

The previous prime is 18979. The next prime is 19001. The reversal of 18990 is 9981.

18990 is nontrivially palindromic in base 14.

It is an interprime number because it is at equal distance from previous prime (18979) and next prime (19001).

It is a zygodrome in base 3.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16 + ... + 195.

It is an arithmetic number, because the mean of its divisors is an integer number (2067).

218990 is an apocalyptic number.

18990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24804).

18990 is an abundant number, since it is smaller than the sum of its proper divisors (30618).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18990 is a wasteful number, since it uses less digits than its factorization.

18990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224 (or 221 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 18990 is about 137.8042089343. The cubic root of 18990 is about 26.6793342593.

Subtracting from 18990 its reverse (9981), we obtain a palindrome (9009).

The spelling of 18990 in words is "eighteen thousand, nine hundred ninety".

Divisors: 1 2 3 5 6 9 10 15 18 30 45 90 211 422 633 1055 1266 1899 2110 3165 3798 6330 9495 18990