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21222221 = 1910111059
BaseRepresentation
bin101000011110…
…1001101001101
31110221012102012
41100331031031
520413102341
62034511005
7345246236
oct120751515
943835365
1021222221
1110a85629
127135465
134520837
142b6608d
151ce30eb
hex143d34d

21222221 has 8 divisors (see below), whose sum is σ = 22562400. Its totient is φ = 19904400.

The previous prime is 21222211. The next prime is 21222251. The reversal of 21222221 is 12222212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21222221 - 218 = 20960077 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21222196 and 21222205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3611 + ... + 7448.

It is an arithmetic number, because the mean of its divisors is an integer number (2820300).

Almost surely, 221222221 is an apocalyptic number.

It is an amenable number.

21222221 is a deficient number, since it is larger than the sum of its proper divisors (1340179).

21222221 is a wasteful number, since it uses less digits than its factorization.

21222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11179.

The product of its digits is 64, while the sum is 14.

The square root of 21222221 is about 4606.7581877064. The cubic root of 21222221 is about 276.8621651740.

Adding to 21222221 its reverse (12222212), we get a palindrome (33444433).

Subtracting from 21222221 its reverse (12222212), we obtain a palindrome (9000009).

It can be divided in two parts, 2 and 1222221, that multiplied together give a palindrome (2444442).

The spelling of 21222221 in words is "twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".

Divisors: 1 19 101 1919 11059 210121 1116959 21222221