| Base | Representation |
|---|---|
| bin | 10100000010110011… |
| … | …000100111110100000 |
| 3 | 2001112220000201211200 |
| 4 | 110002303010332200 |
| 5 | 323034033440030 |
| 6 | 13515330241200 |
| 7 | 1361221055103 |
| oct | 240263047640 |
| 9 | 61486021750 |
| 10 | 21521780640 |
| 11 | 9144536378 |
| 12 | 4207726200 |
| 13 | 204ca54959 |
| 14 | 108245873a |
| 15 | 85e668d60 |
| hex | 502cc4fa0 |
21521780640 has 288 divisors, whose sum is σ = 74646411840. Its totient is φ = 5645832192.
The previous prime is 21521780633. The next prime is 21521780647. The reversal of 21521780640 is 4608712512.
21521780640 is a `hidden beast` number, since 2 + 1 + 5 + 2 + 1 + 7 + 8 + 0 + 640 = 666.
It is an interprime number because it is at equal distance from previous prime (21521780633) and next prime (21521780647).
It is a tau number, because it is divible by the number of its divisors (288).
It is a Harshad number since it is a multiple of its sum of digits (36).
It is a junction number, because it is equal to n+sod(n) for n = 21521780595 and 21521780604.
It is not an unprimeable number, because it can be changed into a prime (21521780647) by changing a digit.
It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39344847 + ... + 39345393.
It is an arithmetic number, because the mean of its divisors is an integer number (259188930).
Almost surely, 221521780640 is an apocalyptic number.
21521780640 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 21521780640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37323205920).
21521780640 is an abundant number, since it is smaller than the sum of its proper divisors (53124631200).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21521780640 is a wasteful number, since it uses less digits than its factorization.
21521780640 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 964 (or 953 counting only the distinct ones).
The product of its (nonzero) digits is 26880, while the sum is 36.
The spelling of 21521780640 in words is "twenty-one billion, five hundred twenty-one million, seven hundred eighty thousand, six hundred forty".
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