| Base | Representation |
|---|---|
| bin | 101001011011… |
| … | …1000100110000 |
| 3 | 1111212120011000 |
| 4 | 1102313010300 |
| 5 | 21030041032 |
| 6 | 2053322000 |
| 7 | 352425450 |
| oct | 122670460 |
| 9 | 44776130 |
| 10 | 21721392 |
| 11 | 11296670 |
| 12 | 7336300 |
| 13 | 4666ac4 |
| 14 | 2c55d60 |
| 15 | 1d90e7c |
| hex | 14b7130 |
21721392 has 160 divisors (see below), whose sum is σ = 77852160. Its totient is φ = 5633280.
The previous prime is 21721387. The next prime is 21721397. The reversal of 21721392 is 29312712.
It is an interprime number because it is at equal distance from previous prime (21721387) and next prime (21721397).
It is a Harshad number since it is a multiple of its sum of digits (27).
It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.
It is not an unprimeable number, because it can be changed into a prime (21721397) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32938 + ... + 33590.
It is an arithmetic number, because the mean of its divisors is an integer number (486576).
Almost surely, 221721392 is an apocalyptic number.
21721392 is a gapful number since it is divisible by the number (22) 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 21721392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38926080).
21721392 is an abundant number, since it is smaller than the sum of its proper divisors (56130768).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21721392 is a wasteful number, since it uses less digits than its factorization.
21721392 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 688 (or 676 counting only the distinct ones).
The product of its digits is 1512, while the sum is 27.
The square root of 21721392 is about 4660.6214177940. The cubic root of 21721392 is about 279.0160702964.
It can be divided in two parts, 217 and 21392, that added together give a square (21609 = 1472).
The spelling of 21721392 in words is "twenty-one million, seven hundred twenty-one thousand, three hundred ninety-two".
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