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20720215 = 54144043
BaseRepresentation
bin100111100001…
…0101001010111
31102222200210101
41033002221113
520301021330
62020034531
7341055535
oct117025127
942880711
1020720215
111077244a
126b32a47
1343a61a9
142a75155
151c444ca
hex13c2a57

20720215 has 4 divisors (see below), whose sum is σ = 24864264. Its totient is φ = 16576168.

The previous prime is 20720209. The next prime is 20720221. The reversal of 20720215 is 51202702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51202702 = 225601351.

It is an interprime number because it is at equal distance from previous prime (20720209) and next prime (20720221).

It is a cyclic number.

It is not a de Polignac number, because 20720215 - 27 = 20720087 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20720192 and 20720201.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 2072017 + ... + 2072026.

It is an arithmetic number, because the mean of its divisors is an integer number (6216066).

Almost surely, 220720215 is an apocalyptic number.

20720215 is a deficient number, since it is larger than the sum of its proper divisors (4144049).

20720215 is an equidigital number, since it uses as much as digits as its factorization.

20720215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4144048.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 20720215 is about 4551.9462870293. The cubic root of 20720215 is about 274.6616886554.

Adding to 20720215 its reverse (51202702), we get a palindrome (71922917).

The spelling of 20720215 in words is "twenty million, seven hundred twenty thousand, two hundred fifteen".

Divisors: 1 5 4144043 20720215