21121012121 has 16 divisors (see below), whose sum is σ = 23304189888. Its totient is φ = 18982118400.

The previous prime is 21121012103. The next prime is 21121012189. The reversal of 21121012121 is 12121012112.

It is a cyclic number.

It is not a de Polignac number, because 21121012121 - 2¹⁴ = 21120995737 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121012096 and 21121012105.

It is not an unprimeable number, because it can be changed into a prime (21121012021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1006466 + ... + 1027236.

It is an arithmetic number, because the mean of its divisors is an integer number (1456511868).

Almost surely, 2^21121012121 is an apocalyptic number.

It is an amenable number.

21121012121 is a deficient number, since it is larger than the sum of its proper divisors (2183177767).

21121012121 is a wasteful number, since it uses less digits than its factorization.

21121012121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21832.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21121012121 its reverse (12121012112), we get a palindrome (33242024233).

Subtracting from 21121012121 its reverse (12121012112), we obtain a palindrome (9000000009).

The spelling of 21121012121 in words is "twenty-one billion, one hundred twenty-one million, twelve thousand, one hundred twenty-one".