21002121222221 has 8 divisors (see below), whose sum is σ = 21390542017824. Its totient is φ = 20616923836080.

The previous prime is 21002121222149. The next prime is 21002121222233. The reversal of 21002121222221 is 12222212120012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002121222221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21002121222193 and 21002121222202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002121222421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 805839215 + ... + 805865276.

It is an arithmetic number, because the mean of its divisors is an integer number (2673817752228).

Almost surely, 2^{21002121222221} is an apocalyptic number.

It is an amenable number.

21002121222221 is a deficient number, since it is larger than the sum of its proper divisors (388420795603).

21002121222221 is a wasteful number, since it uses less digits than its factorization.

21002121222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1611704731.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21002121222221 its reverse (12222212120012), we get a palindrome (33224333342233).

The spelling of 21002121222221 in words is "twenty-one trillion, two billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".