211221421 has 2 divisors, whose sum is σ = 211221422. Its totient is φ = 211221420.

The previous prime is 211221371. The next prime is 211221469. The reversal of 211221421 is 124122112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 150552900 + 60668521 = 12270^2 + 7789^2 .

It is a cyclic number.

It is not a de Polignac number, because 211221421 - 2⁹ = 211220909 is a prime.

It is a super-2 number, since 2×211221421² = 89228977378518482, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 211221395 and 211221404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211227421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105610710 + 105610711.

It is an arithmetic number, because the mean of its divisors is an integer number (105610711).

Almost surely, 2^211221421 is an apocalyptic number.

It is an amenable number.

211221421 is a deficient number, since it is larger than the sum of its proper divisors (1).

211221421 is an equidigital number, since it uses as much as digits as its factorization.

211221421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64, while the sum is 16.

The square root of 211221421 is about 14533.4586730069. The cubic root of 211221421 is about 595.5423541522.

Adding to 211221421 its reverse (124122112), we get a palindrome (335343533).

The spelling of 211221421 in words is "two hundred eleven million, two hundred twenty-one thousand, four hundred twenty-one".