21221535353551 has 16 divisors (see below), whose sum is σ = 22916047845600. Its totient is φ = 19535907063168.

The previous prime is 21221535353509. The next prime is 21221535353597. The reversal of 21221535353551 is 15535353512212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21221535353551 - 2¹⁷ = 21221535222479 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221535353498 and 21221535353507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221535350551) 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, 34828945 + ... + 35433013.

It is an arithmetic number, because the mean of its divisors is an integer number (1432252990350).

Almost surely, 2^{21221535353551} is an apocalyptic number.

21221535353551 is a deficient number, since it is larger than the sum of its proper divisors (1694512492049).

21221535353551 is a wasteful number, since it uses less digits than its factorization.

21221535353551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611418.

The product of its digits is 675000, while the sum is 43.

Adding to 21221535353551 its reverse (15535353512212), we get a palindrome (36756888865763).

The spelling of 21221535353551 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred thirty-five million, three hundred fifty-three thousand, five hundred fifty-one".