21221002012221 has 24 divisors (see below), whose sum is σ = 35406163787904. Its totient is φ = 12104671378560.

The previous prime is 21221002012183. The next prime is 21221002012241. The reversal of 21221002012221 is 12221020012212.

It is a happy number.

21221002012221 is a `hidden beast` number, since 21 + 221 + 0 + 0 + 201 + 2 + 221 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-21221002012221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221002012194 and 21221002012203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221002012241) 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 23 ways as a sum of consecutive naturals, for example, 6304514661 + ... + 6304518026.

It is an arithmetic number, because the mean of its divisors is an integer number (1475256824496).

Almost surely, 2^{21221002012221} is an apocalyptic number.

It is an amenable number.

21221002012221 is a deficient number, since it is larger than the sum of its proper divisors (14185161775683).

21221002012221 is a wasteful number, since it uses less digits than its factorization.

21221002012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12609032721 (or 12609032718 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21221002012221 its reverse (12221020012212), we get a palindrome (33442022024433).

Subtracting from 21221002012221 its reverse (12221020012212), we obtain a square (8999982000009 = 2999997²).

The spelling of 21221002012221 in words is "twenty-one trillion, two hundred twenty-one billion, two million, twelve thousand, two hundred twenty-one".