21506205522242 has 8 divisors (see below), whose sum is σ = 36867780895296. Its totient is φ = 9216945223812.

The previous prime is 21506205522203. The next prime is 21506205522247. The reversal of 21506205522242 is 24222550260512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21506205522196 and 21506205522205.

It is not an unprimeable number, because it can be changed into a prime (21506205522247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 768078768638 + ... + 768078768665.

It is an arithmetic number, because the mean of its divisors is an integer number (4608472611912).

Almost surely, 2^{21506205522242} is an apocalyptic number.

21506205522242 is a deficient number, since it is larger than the sum of its proper divisors (15361575373054).

21506205522242 is a wasteful number, since it uses less digits than its factorization.

21506205522242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1536157537312.

The product of its (nonzero) digits is 192000, while the sum is 38.

Adding to 21506205522242 its reverse (24222550260512), we get a palindrome (45728755782754).

The spelling of 21506205522242 in words is "twenty-one trillion, five hundred six billion, two hundred five million, five hundred twenty-two thousand, two hundred forty-two".