21010 has 16 divisors (see below), whose sum is σ = 41472. Its totient is φ = 7600.

The previous prime is 21001. The next prime is 21011. The reversal of 21010 is 1012.

21010 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

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

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15 + ... + 205.

It is an arithmetic number, because the mean of its divisors is an integer number (2592).

2²¹⁰¹⁰ is an apocalyptic number.

21010 is a deficient number, since it is larger than the sum of its proper divisors (20462).

21010 is a wasteful number, since it uses less digits than its factorization.

21010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209.

The product of its (nonzero) digits is 2, while the sum is 4.

The square root of 21010 is about 144.9482666333. The cubic root of 21010 is about 27.5936203136.

Adding to 21010 its reverse (1012), we get a palindrome (22022).

The spelling of 21010 in words is "twenty-one thousand, ten", and thus it is an iban number.