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21002421 = 31137103167
BaseRepresentation
bin101000000011…
…1100010110101
31110112000220110
41100013202311
520334034141
62030053233
7343342356
oct120074265
943460813
1021002421
1110945480
12704a219
13447478b
142b09d2d
151c9ce16
hex14078b5

21002421 has 32 divisors (see below), whose sum is σ = 31868928. Its totient is φ = 12191040.

The previous prime is 21002413. The next prime is 21002431. The reversal of 21002421 is 12420012.

It is not a de Polignac number, because 21002421 - 23 = 21002413 is a prime.

It is a super-2 number, since 2×210024212 = 882203375722482, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21002397 and 21002406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002431) 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, 125680 + ... + 125846.

It is an arithmetic number, because the mean of its divisors is an integer number (995904).

Almost surely, 221002421 is an apocalyptic number.

It is an amenable number.

21002421 is a deficient number, since it is larger than the sum of its proper divisors (10866507).

21002421 is a wasteful number, since it uses less digits than its factorization.

21002421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321.

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21002421 is about 4582.8398400991. The cubic root of 21002421 is about 275.9030193822.

Adding to 21002421 its reverse (12420012), we get a palindrome (33422433).

The spelling of 21002421 in words is "twenty-one million, two thousand, four hundred twenty-one".

Divisors: 1 3 11 33 37 103 111 167 309 407 501 1133 1221 1837 3399 3811 5511 6179 11433 17201 18537 41921 51603 67969 125763 189211 203907 567633 636437 1909311 7000807 21002421