21221235 has 24 divisors (see below), whose sum is σ = 42038880. Its totient is φ = 9700992.

The previous prime is 21221171. The next prime is 21221237. The reversal of 21221235 is 53212212.

It is not a de Polignac number, because 21221235 - 2⁶ = 21221171 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221237) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33370 + ... + 33999.

It is an arithmetic number, because the mean of its divisors is an integer number (1751620).

Almost surely, 2^21221235 is an apocalyptic number.

21221235 is a deficient number, since it is larger than the sum of its proper divisors (20817645).

21221235 is a wasteful number, since it uses less digits than its factorization.

21221235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67387 (or 67384 counting only the distinct ones).

The product of its digits is 240, while the sum is 18.

The square root of 21221235 is about 4606.6511697762. The cubic root of 21221235 is about 276.8578773677.

Adding to 21221235 its reverse (53212212), we get a palindrome (74433447).

The spelling of 21221235 in words is "twenty-one million, two hundred twenty-one thousand, two hundred thirty-five".