211221430021 has 6 divisors (see below), whose sum is σ = 245706561510. Its totient is φ = 181046939976.

The previous prime is 211221430003. The next prime is 211221430037. The reversal of 211221430021 is 120034122112.

It can be written as a sum of positive squares in only one way, i.e., 200045980225 + 11175449796 = 447265^2 + 105714^2 .

It is not a de Polignac number, because 211221430021 - 2¹¹ = 211221427973 is a prime.

It is a super-2 number, since 2×211221430021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211221436021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2155320666 + ... + 2155320763.

It is an arithmetic number, because the mean of its divisors is an integer number (40951093585).

Almost surely, 2^211221430021 is an apocalyptic number.

It is an amenable number.

211221430021 is a deficient number, since it is larger than the sum of its proper divisors (34485131489).

211221430021 is an equidigital number, since it uses as much as digits as its factorization.

211221430021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310641443 (or 4310641436 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 211221430021 its reverse (120034122112), we get a palindrome (331255552133).

The spelling of 211221430021 in words is "two hundred eleven billion, two hundred twenty-one million, four hundred thirty thousand, twenty-one".