21221202112121 has 16 divisors (see below), whose sum is σ = 23335741605888. Its totient is φ = 19137592252800.

The previous prime is 21221202112093. The next prime is 21221202112207. The reversal of 21221202112121 is 12121120212212.

It is a cyclic number.

It is not a de Polignac number, because 21221202112121 - 2¹⁰ = 21221202111097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221202112093 and 21221202112102.

It is not an unprimeable number, because it can be changed into a prime (21221202412121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9729311 + ... + 11709051.

It is an arithmetic number, because the mean of its divisors is an integer number (1458483850368).

Almost surely, 2^{21221202112121} is an apocalyptic number.

It is an amenable number.

21221202112121 is a deficient number, since it is larger than the sum of its proper divisors (2114539493767).

21221202112121 is a wasteful number, since it uses less digits than its factorization.

21221202112121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1987552.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21221202112121 its reverse (12121120212212), we get a palindrome (33342322324333).

The spelling of 21221202112121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred two million, one hundred twelve thousand, one hundred twenty-one".