21212135 has 16 divisors (see below), whose sum is σ = 29194752. Its totient is φ = 14493600.

The previous prime is 21212131. The next prime is 21212143. The reversal of 21212135 is 53121212.

It is a happy number.

It is not a de Polignac number, because 21212135 - 2² = 21212131 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212131) 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, 10670 + ... + 12500.

It is an arithmetic number, because the mean of its divisors is an integer number (1824672).

Almost surely, 2^21212135 is an apocalyptic number.

21212135 is a deficient number, since it is larger than the sum of its proper divisors (7982617).

21212135 is a wasteful number, since it uses less digits than its factorization.

21212135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2174.

The product of its digits is 120, while the sum is 17.

The square root of 21212135 is about 4605.6633615582. The cubic root of 21212135 is about 276.8182980361.

Adding to 21212135 its reverse (53121212), we get a palindrome (74333347).

The spelling of 21212135 in words is "twenty-one million, two hundred twelve thousand, one hundred thirty-five".