211121210021 has 4 divisors (see below), whose sum is σ = 215104629132. Its totient is φ = 207137790912.

The previous prime is 211121210011. The next prime is 211121210101. The reversal of 211121210021 is 120012121112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 99468328996 + 111652881025 = 315386^2 + 334145^2 .

It is a cyclic number.

It is not a de Polignac number, because 211121210021 - 2³⁴ = 193941340837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 211121209978 and 211121210005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211121210011) 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 3 ways as a sum of consecutive naturals, for example, 1991709476 + ... + 1991709581.

It is an arithmetic number, because the mean of its divisors is an integer number (53776157283).

Almost surely, 2^211121210021 is an apocalyptic number.

It is an amenable number.

211121210021 is a deficient number, since it is larger than the sum of its proper divisors (3983419111).

211121210021 is an equidigital number, since it uses as much as digits as its factorization.

211121210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3983419110.

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

Adding to 211121210021 its reverse (120012121112), we get a palindrome (331133331133).

The spelling of 211121210021 in words is "two hundred eleven billion, one hundred twenty-one million, two hundred ten thousand, twenty-one".