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20810405 = 5711191283
BaseRepresentation
bin100111101100…
…0101010100101
31110011021111202
41033120222211
520311413110
62022012245
7341612510
oct117305245
943137452
1020810405
1110824190
126b77085
134408265
142a99d77
151c610a5
hex13d8aa5

20810405 has 32 divisors (see below), whose sum is σ = 31408128. Its totient is φ = 12859200.

The previous prime is 20810399. The next prime is 20810407. The reversal of 20810405 is 50401802.

It is not a de Polignac number, because 20810405 - 218 = 20548261 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 (20810407) 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 in 31 ways as a sum of consecutive naturals, for example, 73394 + ... + 73676.

It is an arithmetic number, because the mean of its divisors is an integer number (981504).

Almost surely, 220810405 is an apocalyptic number.

It is an amenable number.

20810405 is a deficient number, since it is larger than the sum of its proper divisors (10597723).

20810405 is a wasteful number, since it uses less digits than its factorization.

20810405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 20810405 is about 4561.8422813596. The cubic root of 20810405 is about 275.0596234356.

It can be divided in two parts, 208 and 10405, that multiplied together give a triangular number (2164240 = T2080).

The spelling of 20810405 in words is "twenty million, eight hundred ten thousand, four hundred five".

Divisors: 1 5 7 11 35 55 77 191 283 385 955 1337 1415 1981 2101 3113 6685 9905 10505 14707 15565 21791 54053 73535 108955 270265 378371 594583 1891855 2972915 4162081 20810405