21002211020221 has 4 divisors (see below), whose sum is σ = 21398479152732. Its totient is φ = 20605942887712.

The previous prime is 21002211020149. The next prime is 21002211020251. The reversal of 21002211020221 is 12202011220012.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14907212892196 + 6094998128025 = 3860986^2 + 2468805^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002211020221 - 2¹⁵ = 21002210987453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002211020195 and 21002211020204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002211020251) 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, 198134066176 + ... + 198134066281.

It is an arithmetic number, because the mean of its divisors is an integer number (5349619788183).

Almost surely, 2^{21002211020221} is an apocalyptic number.

It is an amenable number.

21002211020221 is a deficient number, since it is larger than the sum of its proper divisors (396268132511).

21002211020221 is an equidigital number, since it uses as much as digits as its factorization.

21002211020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396268132510.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21002211020221 its reverse (12202011220012), we get a palindrome (33204222240233).

The spelling of 21002211020221 in words is "twenty-one trillion, two billion, two hundred eleven million, twenty thousand, two hundred twenty-one".