| Base | Representation |
|---|---|
| bin | 10011110000010110… |
| … | …001111011000110100 |
| 3 | 2000202022112222212100 |
| 4 | 103300112033120310 |
| 5 | 321420312344340 |
| 6 | 13424511422100 |
| 7 | 1350441663465 |
| oct | 236026173064 |
| 9 | 60668488770 |
| 10 | 21212231220 |
| 11 | 8aa582a304 |
| 12 | 413bb24930 |
| 13 | 200089240b |
| 14 | 10532bad6c |
| 15 | 8423c0830 |
| hex | 4f058f634 |
21212231220 has 144 divisors (see below), whose sum is σ = 65724946560. Its totient is φ = 5536339200.
The previous prime is 21212231207. The next prime is 21212231231. The reversal of 21212231220 is 2213221212.
21212231220 is a `hidden beast` number, since 2 + 1 + 212 + 231 + 220 = 666.
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 = 21212231193 and 21212231202.
It is a congruent number.
It is an unprimeable number.
It is a pernicious number, because its binary representation contains a prime number (17) of ones.
It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1770450 + ... + 1782390.
It is an arithmetic number, because the mean of its divisors is an integer number (456423240).
Almost surely, 221212231220 is an apocalyptic number.
21212231220 is a gapful number since it is divisible by the number (20) 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 21212231220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32862473280).
21212231220 is an abundant number, since it is smaller than the sum of its proper divisors (44512715340).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21212231220 is a wasteful number, since it uses less digits than its factorization.
21212231220 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 12166 (or 12161 counting only the distinct ones).
The product of its (nonzero) digits is 192, while the sum is 18.
Adding to 21212231220 its reverse (2213221212), we get a palindrome (23425452432).
It can be divided in two parts, 212122 and 31220, that added together give a palindrome (243342).
The spelling of 21212231220 in words is "twenty-one billion, two hundred twelve million, two hundred thirty-one thousand, two hundred twenty".
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