21054 has 24 divisors (see below), whose sum is σ = 47880. Its totient is φ = 6160.

The previous prime is 21031. The next prime is 21059. The reversal of 21054 is 45012.

Added to its reverse (45012) it gives a triangular number (66066 = T₃₆₃).

21054 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an alternating number because its digits alternate between even and odd.

21054 is a Rhonda number in base 9.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21059) by changing a digit.

21054 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 712 + ... + 740.

It is an arithmetic number, because the mean of its divisors is an integer number (1995).

2²¹⁰⁵⁴ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21054, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23940).

21054 is an abundant number, since it is smaller than the sum of its proper divisors (26826).

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

21054 is a wasteful number, since it uses less digits than its factorization.

21054 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21054 is about 145.0999655410. The cubic root of 21054 is about 27.6128694446.

Adding to 21054 its reverse (45012), we get a palindrome (66066).

The spelling of 21054 in words is "twenty-one thousand, fifty-four".