210021 has 16 divisors (see below), whose sum is σ = 326784. Its totient is φ = 117504.

The previous prime is 210019. The next prime is 210031. The reversal of 210021 is 120012.

It is a happy number.

210021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 210021 - 2¹ = 210019 is a prime.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 209991 and 210009.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1465 + ... + 1601.

It is an arithmetic number, because the mean of its divisors is an integer number (20424).

2²¹⁰⁰²¹ is an apocalyptic number.

210021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

210021 is a deficient number, since it is larger than the sum of its proper divisors (116763).

210021 is a wasteful number, since it uses less digits than its factorization.

210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220.

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 210021 is about 458.2804818013. The cubic root of 210021 is about 59.4412007689.

Adding to 210021 its reverse (120012), we get a palindrome (330033).

Subtracting from 210021 its reverse (120012), we obtain a palindrome (90009).

It can be divided in two parts, 2100 and 21, that multiplied together give a square (44100 = 210²).

The spelling of 210021 in words is "two hundred ten thousand, twenty-one", and thus it is an iban number.