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161820 = 223252931
BaseRepresentation
bin100111100000011100
322012222100
4213200130
520134240
63245100
71242531
oct474034
9265870
10161820
1110063a
1279790
1358869
1442d88
1532e30
hex2781c

161820 has 72 divisors (see below), whose sum is σ = 524160. Its totient is φ = 40320.

The previous prime is 161807. The next prime is 161831. The reversal of 161820 is 28161.

161820 = T39 + T40 + ... + T100.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 161793 and 161802.

It is a congruent number.

It is an unprimeable number.

161820 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5205 + ... + 5235.

It is an arithmetic number, because the mean of its divisors is an integer number (7280).

2161820 is an apocalyptic number.

161820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (262080).

161820 is an abundant number, since it is smaller than the sum of its proper divisors (362340).

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

161820 is a wasteful number, since it uses less digits than its factorization.

161820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75 (or 70 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 161820 is about 402.2685670047. The cubic root of 161820 is about 54.4934200737.

Adding to 161820 its reverse (28161), we get a palindrome (189981).

The spelling of 161820 in words is "one hundred sixty-one thousand, eight hundred twenty".

Divisors: 1 2 3 4 5 6 9 10 12 15 18 20 29 30 31 36 45 58 60 62 87 90 93 116 124 145 155 174 180 186 261 279 290 310 348 372 435 465 522 558 580 620 870 899 930 1044 1116 1305 1395 1740 1798 1860 2610 2697 2790 3596 4495 5220 5394 5580 8091 8990 10788 13485 16182 17980 26970 32364 40455 53940 80910 161820