21050 has 12 divisors (see below), whose sum is σ = 39246. Its totient is φ = 8400.

The previous prime is 21031. The next prime is 21059. The reversal of 21050 is 5012.

It can be written as a sum of positive squares in 3 ways, for example, as 8281 + 12769 = 91^2 + 113^2 .

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

It is a Curzon number.

It is a nialpdrome in base 13.

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

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 161 + ... + 260.

2²¹⁰⁵⁰ is an apocalyptic number.

21050 is a deficient number, since it is larger than the sum of its proper divisors (18196).

21050 is a wasteful number, since it uses less digits than its factorization.

21050 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433 (or 428 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 8.

The square root of 21050 is about 145.0861812855. The cubic root of 21050 is about 27.6111206324.

Adding to 21050 its reverse (5012), we get a palindrome (26062).

The spelling of 21050 in words is "twenty-one thousand, fifty".