21206210 has 8 divisors (see below), whose sum is σ = 38171196. Its totient is φ = 8482480.

The previous prime is 21206189. The next prime is 21206219. The reversal of 21206210 is 1260212.

It can be written as a sum of positive squares in 2 ways, for example, as 19386409 + 1819801 = 4403^2 + 1349^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21206219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1060301 + ... + 1060320.

Almost surely, 2^21206210 is an apocalyptic number.

21206210 is a deficient number, since it is larger than the sum of its proper divisors (16964986).

21206210 is a wasteful number, since it uses less digits than its factorization.

21206210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2120628.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21206210 is about 4605.0200868183. The cubic root of 21206210 is about 276.7925218919.

Adding to 21206210 its reverse (1260212), we get a palindrome (22466422).

The spelling of 21206210 in words is "twenty-one million, two hundred six thousand, two hundred ten".