21411 has 16 divisors (see below), whose sum is σ = 34720. Its totient is φ = 12960.

The previous prime is 21407. The next prime is 21419. The reversal of 21411 is 11412.

It is a happy number.

21411 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 21411 - 2² = 21407 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an Ulam number.

It is a Duffinian number.

21411 is a lucky number.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 21393 and 21402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21419) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 321 + ... + 381.

It is an arithmetic number, because the mean of its divisors is an integer number (2170).

2²¹⁴¹¹ is an apocalyptic number.

21411 is a deficient number, since it is larger than the sum of its proper divisors (13309).

21411 is a wasteful number, since it uses less digits than its factorization.

21411 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83 (or 77 counting only the distinct ones).

The product of its digits is 8, while the sum is 9.

The square root of 21411 is about 146.3249807791. The cubic root of 21411 is about 27.7680671242.

Adding to 21411 its reverse (11412), we get a palindrome (32823).

Subtracting from 21411 its reverse (11412), we obtain a palindrome (9999).

It can be divided in two parts, 214 and 11, that added together give a square (225 = 15²).

The spelling of 21411 in words is "twenty-one thousand, four hundred eleven", and thus it is an iban number.