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21955709 is a prime number
BaseRepresentation
bin101001111000…
…0010001111101
31112022110120102
41103300101331
521110040314
62102330445
7354422546
oct123602175
945273512
1021955709
1111436716
127429a25
134719659
142cb74cd
151dda5de
hex14f047d

21955709 has 2 divisors, whose sum is σ = 21955710. Its totient is φ = 21955708.

The previous prime is 21955691. The next prime is 21955711. The reversal of 21955709 is 90755912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14784025 + 7171684 = 3845^2 + 2678^2 .

It is a cyclic number.

It is not a de Polignac number, because 21955709 - 212 = 21951613 is a prime.

Together with 21955711, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21955799) 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 as a sum of consecutive naturals, namely, 10977854 + 10977855.

It is an arithmetic number, because the mean of its divisors is an integer number (10977855).

Almost surely, 221955709 is an apocalyptic number.

It is an amenable number.

21955709 is a deficient number, since it is larger than the sum of its proper divisors (1).

21955709 is an equidigital number, since it uses as much as digits as its factorization.

21955709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28350, while the sum is 38.

The square root of 21955709 is about 4685.6919446332. The cubic root of 21955709 is about 280.0157686698.

The spelling of 21955709 in words is "twenty-one million, nine hundred fifty-five thousand, seven hundred nine".