21021210220121 has 4 divisors (see below), whose sum is σ = 21021225379044. Its totient is φ = 21021195061200.

The previous prime is 21021210220037. The next prime is 21021210220123. The reversal of 21021210220121 is 12102201212012.

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 4390432952896 + 16630777267225 = 2095336^2 + 4078085^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021210220121 - 2¹⁴ = 21021210203737 is a prime.

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 21021210220121.

It is not an unprimeable number, because it can be changed into a prime (21021210220123) 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, 5263490 + ... + 8351451.

It is an arithmetic number, because the mean of its divisors is an integer number (5255306344761).

Almost surely, 2^{21021210220121} is an apocalyptic number.

It is an amenable number.

21021210220121 is a deficient number, since it is larger than the sum of its proper divisors (15158923).

21021210220121 is a wasteful number, since it uses less digits than its factorization.

21021210220121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15158922.

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

Adding to 21021210220121 its reverse (12102201212012), we get a palindrome (33123411432133).

The spelling of 21021210220121 in words is "twenty-one trillion, twenty-one billion, two hundred ten million, two hundred twenty thousand, one hundred twenty-one".