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21012221209 = 72428820841
BaseRepresentation
bin10011100100011011…
…010000110100011001
32000020101012102201011
4103210123100310121
5321013112034314
613353004453521
71342462635100
oct234433206431
960211172634
1021012221209
118a0293a881
1240a4b4a2a1
131c9b3036b5
1410348d5037
1582ea634c4
hex4e46d0d19

21012221209 has 6 divisors (see below), whose sum is σ = 24442787994. Its totient is φ = 18010475280.

The previous prime is 21012221207. The next prime is 21012221311. The reversal of 21012221209 is 90212221012.

It can be written as a sum of positive squares in only one way, i.e., 12187497609 + 8824723600 = 110397^2 + 93940^2 .

It is not a de Polignac number, because 21012221209 - 21 = 21012221207 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21012221209.

It is not an unprimeable number, because it can be changed into a prime (21012221207) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 214410372 + ... + 214410469.

It is an arithmetic number, because the mean of its divisors is an integer number (4073797999).

Almost surely, 221012221209 is an apocalyptic number.

It is an amenable number.

21012221209 is a deficient number, since it is larger than the sum of its proper divisors (3430566785).

21012221209 is an equidigital number, since it uses as much as digits as its factorization.

21012221209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428820855 (or 428820848 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The spelling of 21012221209 in words is "twenty-one billion, twelve million, two hundred twenty-one thousand, two hundred nine".

Divisors: 1 7 49 428820841 3001745887 21012221209