21020121211 has 16 divisors (see below), whose sum is σ = 22640292000. Its totient is φ = 19455724800.

The previous prime is 21020121197. The next prime is 21020121229. The reversal of 21020121211 is 11212102012.

It is a cyclic number.

It is not a de Polignac number, because 21020121211 - 2⁵ = 21020121179 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020121191 and 21020121200.

It is not an unprimeable number, because it can be changed into a prime (21020121511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111831 + ... + 233551.

It is an arithmetic number, because the mean of its divisors is an integer number (1415018250).

Almost surely, 2^21020121211 is an apocalyptic number.

21020121211 is a deficient number, since it is larger than the sum of its proper divisors (1620170789).

21020121211 is a wasteful number, since it uses less digits than its factorization.

21020121211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121950.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21020121211 its reverse (11212102012), we get a palindrome (32232223223).

The spelling of 21020121211 in words is "twenty-one billion, twenty million, one hundred twenty-one thousand, two hundred eleven".