211231210021 has 4 divisors (see below), whose sum is σ = 227479764652. Its totient is φ = 194982655392.

The previous prime is 211231209991. The next prime is 211231210039. The reversal of 211231210021 is 120012132112.

211231210021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 98667604996 + 112563605025 = 314114^2 + 335505^2 .

It is a cyclic number.

It is not a de Polignac number, because 211231210021 - 2⁵ = 211231209989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 211231209977 and 211231210004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211231210081) 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 3 ways as a sum of consecutive naturals, for example, 8124277296 + ... + 8124277321.

It is an arithmetic number, because the mean of its divisors is an integer number (56869941163).

Almost surely, 2^211231210021 is an apocalyptic number.

It is an amenable number.

211231210021 is a deficient number, since it is larger than the sum of its proper divisors (16248554631).

211231210021 is a wasteful number, since it uses less digits than its factorization.

211231210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16248554630.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 211231210021 its reverse (120012132112), we get a palindrome (331243342133).

The spelling of 211231210021 in words is "two hundred eleven billion, two hundred thirty-one million, two hundred ten thousand, twenty-one".