21211210 has 8 divisors (see below), whose sum is σ = 38180196. Its totient is φ = 8484480.

The previous prime is 21211181. The next prime is 21211217. The reversal of 21211210 is 1211212.

It can be written as a sum of positive squares in 2 ways, for example, as 19616041 + 1595169 = 4429^2 + 1263^2 .

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

It is a Harshad number since it is a multiple of its sum of digits (10), and also a Moran number because the ratio is a prime number: 2121121 = 21211210 / (2 + 1 + 2 + 1 + 1 + 2 + 1 + 0).

It is not an unprimeable number, because it can be changed into a prime (21211217) 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, 1060551 + ... + 1060570.

Almost surely, 2^21211210 is an apocalyptic number.

21211210 is a deficient number, since it is larger than the sum of its proper divisors (16968986).

21211210 is a wasteful number, since it uses less digits than its factorization.

21211210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2121128.

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

The square root of 21211210 is about 4605.5629406187. The cubic root of 21211210 is about 276.8142742285.

Adding to 21211210 its reverse (1211212), we get a palindrome (22422422).

The spelling of 21211210 in words is "twenty-one million, two hundred eleven thousand, two hundred ten".