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221220 = 223251229
BaseRepresentation
bin110110000000100100
3102020110100
4312000210
524034340
64424100
71610646
oct660044
9366410
10221220
1114122a
12a8030
13798cc
145a896
1545830
hex36024

221220 has 36 divisors (see below), whose sum is σ = 671580. Its totient is φ = 58944.

The previous prime is 221219. The next prime is 221227. The reversal of 221220 is 22122.

It can be written as a sum of positive squares in 2 ways, for example, as 166464 + 54756 = 408^2 + 234^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a zygodrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (221227) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 435 + ... + 794.

It is an arithmetic number, because the mean of its divisors is an integer number (18655).

2221220 is an apocalyptic number.

221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221220 is an abundant number, since it is smaller than the sum of its proper divisors (450360).

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

221220 is a wasteful number, since it uses less digits than its factorization.

221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244 (or 1239 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 221220 is about 470.3403023344. The cubic root of 221220 is about 60.4794912614.

Adding to 221220 its reverse (22122), we get a palindrome (243342).

It can be divided in two parts, 221 and 220, that added together give a square (441 = 212).

The spelling of 221220 in words is "two hundred twenty-one thousand, two hundred twenty", and thus it is an iban number.

Divisors: 1 2 3 4 5 6 9 10 12 15 18 20 30 36 45 60 90 180 1229 2458 3687 4916 6145 7374 11061 12290 14748 18435 22122 24580 36870 44244 55305 73740 110610 221220