21002202122021 has 4 divisors (see below), whose sum is σ = 21002513420844. Its totient is φ = 21001890823200.

The previous prime is 21002202121987. The next prime is 21002202122047. The reversal of 21002202122021 is 12022120220012.

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 12540706533796 + 8461495588225 = 3541286^2 + 2908865^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002202122021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002202122081) 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, 155548190 + ... + 155683151.

It is an arithmetic number, because the mean of its divisors is an integer number (5250628355211).

Almost surely, 2^{21002202122021} is an apocalyptic number.

It is an amenable number.

21002202122021 is a deficient number, since it is larger than the sum of its proper divisors (311298823).

21002202122021 is an equidigital number, since it uses as much as digits as its factorization.

21002202122021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311298822.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21002202122021 its reverse (12022120220012), we get a palindrome (33024322342033).

The spelling of 21002202122021 in words is "twenty-one trillion, two billion, two hundred two million, one hundred twenty-two thousand, twenty-one".