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21519 = 33797
BaseRepresentation
bin101010000001111
31002112000
411100033
51142034
6243343
7116511
oct52017
932460
1021519
1115193
1210553
139a44
147bb1
156599
hex540f

21519 has 8 divisors (see below), whose sum is σ = 31920. Its totient is φ = 14328.

The previous prime is 21517. The next prime is 21521. The reversal of 21519 is 91512.

It is an interprime number because it is at equal distance from previous prime (21517) and next prime (21521).

It is not a de Polignac number, because 21519 - 21 = 21517 is a prime.

It is a super-2 number, since 2×215192 = 926134722, which contains 22 as substring.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 372 + ... + 425.

It is an arithmetic number, because the mean of its divisors is an integer number (3990).

221519 is an apocalyptic number.

21519 is a deficient number, since it is larger than the sum of its proper divisors (10401).

21519 is an equidigital number, since it uses as much as digits as its factorization.

21519 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 806 (or 800 counting only the distinct ones).

The product of its digits is 90, while the sum is 18.

The square root of 21519 is about 146.6935581408. The cubic root of 21519 is about 27.8146774796.

Adding to 21519 its product of digits (90), we get a square (21609 = 1472).

It can be divided in two parts, 2 and 1519, that added together give a square (1521 = 392).

The spelling of 21519 in words is "twenty-one thousand, five hundred nineteen".

Divisors: 1 3 9 27 797 2391 7173 21519