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20209687 = 173116819
BaseRepresentation
bin100110100011…
…0000000010111
31102000202110221
41031012000113
520133202222
62001055211
7333531241
oct115060027
942022427
1020209687
1110453923
126927507
1342579c4
142981091
151b930c7
hex1346017

20209687 has 4 divisors (see below), whose sum is σ = 20326680. Its totient is φ = 20092696.

The previous prime is 20209681. The next prime is 20209691. The reversal of 20209687 is 78690202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78690202 = 239345101.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-20209687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20209681) 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, 58237 + ... + 58582.

It is an arithmetic number, because the mean of its divisors is an integer number (5081670).

Almost surely, 220209687 is an apocalyptic number.

20209687 is a deficient number, since it is larger than the sum of its proper divisors (116993).

20209687 is a wasteful number, since it uses less digits than its factorization.

20209687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116992.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 20209687 is about 4495.5185462858. The cubic root of 20209687 is about 272.3870957235.

Adding to 20209687 its reverse (78690202), we get a palindrome (98899889).

The spelling of 20209687 in words is "twenty million, two hundred nine thousand, six hundred eighty-seven".

Divisors: 1 173 116819 20209687