21364 has 18 divisors (see below), whose sum is σ = 43890. Its totient is φ = 9072.

The previous prime is 21347. The next prime is 21377. The reversal of 21364 is 46312.

It can be written as a sum of positive squares in only one way, i.e., 19600 + 1764 = 140^2 + 42^2 .

It is a d-powerful number, because it can be written as 2⁷ + 1 + 3⁹ + 6⁴ + 4⁴ .

It is a nialpdrome in base 13.

It is a zygodrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 142 + ... + 250.

2²¹³⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21945).

21364 is an abundant number, since it is smaller than the sum of its proper divisors (22526).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21364 is a wasteful number, since it uses less digits than its factorization.

21364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127 (or 118 counting only the distinct ones).

The product of its digits is 144, while the sum is 16.

The square root of 21364 is about 146.1642911247. The cubic root of 21364 is about 27.7477340357.

Adding to 21364 its reverse (46312), we get a palindrome (67676).

The spelling of 21364 in words is "twenty-one thousand, three hundred sixty-four".