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21909071 = 191153109
BaseRepresentation
bin101001110010…
…0111001001111
31112020002121002
41103210321033
521102042241
62101330515
7354136562
oct123447117
945202532
1021909071
1111404678
127406a3b
134701362
142ca44d9
151dcb89b
hex14e4e4f

21909071 has 4 divisors (see below), whose sum is σ = 23062200. Its totient is φ = 20755944.

The previous prime is 21909029. The next prime is 21909077. The reversal of 21909071 is 17090912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21909071 - 218 = 21646927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909077) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 576536 + ... + 576573.

It is an arithmetic number, because the mean of its divisors is an integer number (5765550).

Almost surely, 221909071 is an apocalyptic number.

21909071 is a deficient number, since it is larger than the sum of its proper divisors (1153129).

21909071 is a wasteful number, since it uses less digits than its factorization.

21909071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1153128.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 21909071 is about 4680.7126594142. The cubic root of 21909071 is about 279.8173596335.

Adding to 21909071 its reverse (17090912), we get a palindrome (38999983).

The spelling of 21909071 in words is "twenty-one million, nine hundred nine thousand, seventy-one".

Divisors: 1 19 1153109 21909071