21021021202121 has 4 divisors (see below), whose sum is σ = 21046439608272. Its totient is φ = 20995602795972.

The previous prime is 21021021202063. The next prime is 21021021202177. The reversal of 21021021202121 is 12120212012012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21021021202121 - 2¹⁸ = 21021020939977 is a prime.

It is a super-2 number, since 2×21021021202121² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21021021202121.

It is not an unprimeable number, because it can be changed into a prime (21021021202421) 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, 12709201835 + ... + 12709203488.

It is an arithmetic number, because the mean of its divisors is an integer number (5261609902068).

Almost surely, 2^{21021021202121} is an apocalyptic number.

It is an amenable number.

21021021202121 is a deficient number, since it is larger than the sum of its proper divisors (25418406151).

21021021202121 is an equidigital number, since it uses as much as digits as its factorization.

21021021202121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25418406150.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21021021202121 its reverse (12120212012012), we get a palindrome (33141233214133).

The spelling of 21021021202121 in words is "twenty-one trillion, twenty-one billion, twenty-one million, two hundred two thousand, one hundred twenty-one".