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212831221 is a prime number
BaseRepresentation
bin11001010111110…
…00101111110101
3112211110221112211
430223320233311
5413441044341
633041413421
75163015121
oct1453705765
9484427484
10212831221
11aa157279
125b33a271
133512a745
14203a2581
1513a41181
hexcaf8bf5

212831221 has 2 divisors, whose sum is σ = 212831222. Its totient is φ = 212831220.

The previous prime is 212831207. The next prime is 212831243. The reversal of 212831221 is 122138212.

It is an a-pointer prime, because the next prime (212831243) can be obtained adding 212831221 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190164100 + 22667121 = 13790^2 + 4761^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-212831221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 212831192 and 212831201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212831251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106415610 + 106415611.

It is an arithmetic number, because the mean of its divisors is an integer number (106415611).

Almost surely, 2212831221 is an apocalyptic number.

It is an amenable number.

212831221 is a deficient number, since it is larger than the sum of its proper divisors (1).

212831221 is an equidigital number, since it uses as much as digits as its factorization.

212831221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 22.

The square root of 212831221 is about 14588.7361001562. The cubic root of 212831221 is about 597.0514794833.

Adding to 212831221 its reverse (122138212), we get a palindrome (334969433).

The spelling of 212831221 in words is "two hundred twelve million, eight hundred thirty-one thousand, two hundred twenty-one".