21210210012121 has 8 divisors (see below), whose sum is σ = 22899300565064. Its totient is φ = 19529338878720.

The previous prime is 21210210012091. The next prime is 21210210012127. The reversal of 21210210012121 is 12121001201212.

It can be written as a sum of positive squares in 4 ways, for example, as 61147398400 + 21149062613721 = 247280^2 + 4598811^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21210210012121 - 2¹⁹ = 21210209487833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210210012095 and 21210210012104.

It is not an unprimeable number, because it can be changed into a prime (21210210012127) 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, 2054849520 + ... + 2054859841.

It is an arithmetic number, because the mean of its divisors is an integer number (2862412570633).

Almost surely, 2^{21210210012121} is an apocalyptic number.

It is an amenable number.

21210210012121 is a deficient number, since it is larger than the sum of its proper divisors (1689090552943).

21210210012121 is a wasteful number, since it uses less digits than its factorization.

21210210012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4109709771.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21210210012121 its reverse (12121001201212), we get a palindrome (33331211213333).

The spelling of 21210210012121 in words is "twenty-one trillion, two hundred ten billion, two hundred ten million, twelve thousand, one hundred twenty-one".