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20956 = 2213231

20956 has 18 divisors (see below), whose sum is σ = 40992. Its totient is φ = 9360.

The previous prime is 20947. The next prime is 20959. The reversal of 20956 is 65902.

20956 = T53 + T54 + ... + T64.

20956 is nontrivially palindromic in base 5.

It is a plaindrome in base 14.

It is a nialpdrome in base 13 and base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20959) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 661 + ... + 691.

220956 is an apocalyptic number.

20956 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

20956 is a deficient number, since it is larger than the sum of its proper divisors (20036).

20956 is a wasteful number, since it uses less digits than its factorization.

20956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20956 is about 144.7618734336. The cubic root of 20956 is about 27.5699596138.

The spelling of 20956 in words is "twenty thousand, nine hundred fifty-six".

Divisors: 1 2 4 13 26 31 52 62 124 169 338 403 676 806 1612 5239 10478 20956