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1221011221 is a prime number
BaseRepresentation
bin100100011000111…
…0010011100010101
310011002112210111211
41020301302130111
510000034324341
6321054301421
742154265323
oct11061623425
93132483454
101221011221
11577257891
122a0ab7871
13165c6cc61
14b823cd13
15722db181
hex48c72715

1221011221 has 2 divisors, whose sum is σ = 1221011222. Its totient is φ = 1221011220.

The previous prime is 1221011177. The next prime is 1221011243. The reversal of 1221011221 is 1221101221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1033622500 + 187388721 = 32150^2 + 13689^2 .

It is an emirp because it is prime and its reverse (1221101221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221011221 - 27 = 1221011093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221011251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610505610 + 610505611.

It is an arithmetic number, because the mean of its divisors is an integer number (610505611).

Almost surely, 21221011221 is an apocalyptic number.

It is an amenable number.

1221011221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221011221 is an equidigital number, since it uses as much as digits as its factorization.

1221011221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1221011221 is about 34942.9709813004. The cubic root of 1221011221 is about 1068.8248725814.

Adding to 1221011221 its reverse (1221101221), we get a palindrome (2442112442).

Subtracting 1221011221 from its reverse (1221101221), we obtain a square (90000 = 3002).

The spelling of 1221011221 in words is "one billion, two hundred twenty-one million, eleven thousand, two hundred twenty-one".