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20805985 = 54161197
BaseRepresentation
bin100111101011…
…1100101100001
31110011001110001
41033113211201
520311242420
62021540001
7341563564
oct117274541
943131401
1020805985
1110820932
126b74601
134406245
142a984db
151c5eb0a
hex13d7961

20805985 has 4 divisors (see below), whose sum is σ = 24967188. Its totient is φ = 16644784.

The previous prime is 20805959. The next prime is 20805989. The reversal of 20805985 is 58950802.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6305121 + 14500864 = 2511^2 + 3808^2 .

It is a cyclic number.

It is not a de Polignac number, because 20805985 - 213 = 20797793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20805989) 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, 2080594 + ... + 2080603.

It is an arithmetic number, because the mean of its divisors is an integer number (6241797).

Almost surely, 220805985 is an apocalyptic number.

It is an amenable number.

20805985 is a deficient number, since it is larger than the sum of its proper divisors (4161203).

20805985 is an equidigital number, since it uses as much as digits as its factorization.

20805985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4161202.

The product of its (nonzero) digits is 28800, while the sum is 37.

The square root of 20805985 is about 4561.3578022339. The cubic root of 20805985 is about 275.0401484083.

The spelling of 20805985 in words is "twenty million, eight hundred five thousand, nine hundred eighty-five".

Divisors: 1 5 4161197 20805985