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21220321 = 191116859
BaseRepresentation
bin101000011110…
…0101111100001
31110221002210211
41100330233201
520413022241
62034454121
7345240553
oct120745741
943832724
1021220321
1110a84161
127134341
13451ca05
142b654d3
151ce2781
hex143cbe1

21220321 has 4 divisors (see below), whose sum is σ = 22337200. Its totient is φ = 20103444.

The previous prime is 21220319. The next prime is 21220327. The reversal of 21220321 is 12302212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21220321 - 21 = 21220319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220327) 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 3 ways as a sum of consecutive naturals, for example, 558411 + ... + 558448.

It is an arithmetic number, because the mean of its divisors is an integer number (5584300).

Almost surely, 221220321 is an apocalyptic number.

It is an amenable number.

21220321 is a deficient number, since it is larger than the sum of its proper divisors (1116879).

21220321 is a wasteful number, since it uses less digits than its factorization.

21220321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1116878.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21220321 is about 4606.5519643221. The cubic root of 21220321 is about 276.8539025482.

Adding to 21220321 its reverse (12302212), we get a palindrome (33522533).

The spelling of 21220321 in words is "twenty-one million, two hundred twenty thousand, three hundred twenty-one".

Divisors: 1 19 1116859 21220321