21021202102121 has 8 divisors (see below), whose sum is σ = 23065353831240. Its totient is φ = 19038069827712.

The previous prime is 21021202102099. The next prime is 21021202102123. The reversal of 21021202102121 is 12120120212012.

It can be written as a sum of positive squares in 4 ways, for example, as 8689165212121 + 12332036890000 = 2947739^2 + 3511700^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-21021202102121 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21021202102121.

It is not an unprimeable number, because it can be changed into a prime (21021202102123) 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, 15254862956 + ... + 15254864333.

It is an arithmetic number, because the mean of its divisors is an integer number (2883169228905).

Almost surely, 2^{21021202102121} is an apocalyptic number.

It is an amenable number.

21021202102121 is a deficient number, since it is larger than the sum of its proper divisors (2044151729119).

21021202102121 is a wasteful number, since it uses less digits than its factorization.

21021202102121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30509727355.

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

Adding to 21021202102121 its reverse (12120120212012), we get a palindrome (33141322314133).

The spelling of 21021202102121 in words is "twenty-one trillion, twenty-one billion, two hundred two million, one hundred two thousand, one hundred twenty-one".