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BaseRepresentation
bin101001111010101
31002102212
411033111
51141321
6243205
7116366
oct51725
932385
1021461
1115140
1210505
1399cb
147b6d
15655b
hex53d5

21461 has 4 divisors (see below), whose sum is σ = 23424. Its totient is φ = 19500.

The previous prime is 21433. The next prime is 21467. The reversal of 21461 is 16412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21461 - 26 = 21397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21467) 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, 965 + ... + 986.

It is an arithmetic number, because the mean of its divisors is an integer number (5856).

221461 is an apocalyptic number.

It is an amenable number.

21461 is a deficient number, since it is larger than the sum of its proper divisors (1963).

21461 is a wasteful number, since it uses less digits than its factorization.

21461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1962.

The product of its digits is 48, while the sum is 14.

The square root of 21461 is about 146.4957337263. The cubic root of 21461 is about 27.7896654304.

Adding to 21461 its reverse (16412), we get a palindrome (37873).

The spelling of 21461 in words is "twenty-one thousand, four hundred sixty-one".

Divisors: 1 11 1951 21461