21353434221 has 16 divisors (see below), whose sum is σ = 34251123200. Its totient is φ = 11559753648.

The previous prime is 21353434217. The next prime is 21353434237. The reversal of 21353434221 is 12243435312.

It is not a de Polignac number, because 21353434221 - 2² = 21353434217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21353433221) 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, 26758291 + ... + 26759088.

It is an arithmetic number, because the mean of its divisors is an integer number (2140695200).

Almost surely, 2^21353434221 is an apocalyptic number.

21353434221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21353434221 is a deficient number, since it is larger than the sum of its proper divisors (12897688979).

21353434221 is a wasteful number, since it uses less digits than its factorization.

21353434221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53517408.

The product of its digits is 17280, while the sum is 30.

Adding to 21353434221 its reverse (12243435312), we get a palindrome (33596869533).

The spelling of 21353434221 in words is "twenty-one billion, three hundred fifty-three million, four hundred thirty-four thousand, two hundred twenty-one".