21255551220502 has 4 divisors (see below), whose sum is σ = 31883326830756. Its totient is φ = 10627775610250.

The previous prime is 21255551220481. The next prime is 21255551220557. The reversal of 21255551220502 is 20502215555212.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313887805124 + ... + 5313887805127.

It is an arithmetic number, because the mean of its divisors is an integer number (7970831707689).

Almost surely, 2^{21255551220502} is an apocalyptic number.

21255551220502 is a deficient number, since it is larger than the sum of its proper divisors (10627775610254).

21255551220502 is a wasteful number, since it uses less digits than its factorization.

21255551220502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10627775610253.

The product of its (nonzero) digits is 100000, while the sum is 37.

Adding to 21255551220502 its reverse (20502215555212), we get a palindrome (41757766775714).

The spelling of 21255551220502 in words is "twenty-one trillion, two hundred fifty-five billion, five hundred fifty-one million, two hundred twenty thousand, five hundred two".