| Base | Representation |
|---|---|
| bin | 1001101110001… |
| … | …00010010000000 |
| 3 | 12200102212210000 |
| 4 | 10313010102000 |
| 5 | 131333404240 |
| 6 | 12031440000 |
| 7 | 2010054354 |
| oct | 467042200 |
| 9 | 180385700 |
| 10 | 81544320 |
| 11 | 42036500 |
| 12 | 23386000 |
| 13 | 13b812a0 |
| 14 | ab89464 |
| 15 | 725b430 |
| hex | 4dc4480 |
81544320 has 480 divisors, whose sum is σ = 344712060. Its totient is φ = 18247680.
The previous prime is 81544319. The next prime is 81544321. The reversal of 81544320 is 2344518.
It is an interprime number because it is at equal distance from previous prime (81544319) and next prime (81544321).
It can be written as a sum of positive squares in 2 ways, for example, as 75898944 + 5645376 = 8712^2 + 2376^2 .
It is a tau number, because it is divible by the number of its divisors (480).
It is a super-2 number, since 2×815443202 = 13298952248524800, which contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (27).
It is not an unprimeable number, because it can be changed into a prime (81544321) by changing a digit.
It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 6272634 + ... + 6272646.
Almost surely, 281544320 is an apocalyptic number.
81544320 is a gapful number since it is divisible by the number (80) 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 81544320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172356030).
81544320 is an abundant number, since it is smaller than the sum of its proper divisors (263167740).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
81544320 is a wasteful number, since it uses less digits than its factorization.
81544320 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 66 (or 34 counting only the distinct ones).
The product of its (nonzero) digits is 3840, while the sum is 27.
The square root of 81544320 is about 9030.1893667852. The cubic root of 81544320 is about 433.6418998829.
Adding to 81544320 its reverse (2344518), we get a palindrome (83888838).
The spelling of 81544320 in words is "eighty-one million, five hundred forty-four thousand, three hundred twenty".
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