21621212343252 has 36 divisors (see below), whose sum is σ = 54654395364660. Its totient is φ = 7206968547072.

The previous prime is 21621212343233. The next prime is 21621212343253. The reversal of 21621212343252 is 25234321212612.

21621212343252 is a `hidden beast` number, since 2 + 1 + 6 + 2 + 1 + 212 + 3 + 432 + 5 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3421893226896 + 18199319116356 = 1849836^2 + 4266066^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621212343253) by changing a digit.

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 in 11 ways as a sum of consecutive naturals, for example, 1665003 + ... + 6783410.

Almost surely, 2^{21621212343252} is an apocalyptic number.

It is an amenable number.

21621212343252 is an abundant number, since it is smaller than the sum of its proper divisors (33033183021408).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21621212343252 is a wasteful number, since it uses less digits than its factorization.

21621212343252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8519512 (or 8519507 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

Adding to 21621212343252 its reverse (25234321212612), we get a palindrome (46855533555864).

The spelling of 21621212343252 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred twelve million, three hundred forty-three thousand, two hundred fifty-two".