21450 has 48 divisors (see below), whose sum is σ = 62496. Its totient is φ = 4800.

The previous prime is 21433. The next prime is 21467. The reversal of 21450 is 5412.

21450 is digitally balanced in base 4 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (21433) and next prime (21467).

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

21450 is strictly pandigital in base 6.

It is a Curzon number.

It is a nialpdrome in base 15.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1644 + ... + 1656.

It is an arithmetic number, because the mean of its divisors is an integer number (1302).

2²¹⁴⁵⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31248).

21450 is an abundant number, since it is smaller than the sum of its proper divisors (41046).

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

21450 is a wasteful number, since it uses less digits than its factorization.

21450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39 (or 34 counting only the distinct ones).

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

The square root of 21450 is about 146.4581851588. The cubic root of 21450 is about 27.7849166837.

Adding to 21450 its reverse (5412), we get a palindrome (26862).

The spelling of 21450 in words is "twenty-one thousand, four hundred fifty".