1212210821 has 2 divisors, whose sum is σ = 1212210822. Its totient is φ = 1212210820.

The previous prime is 1212210803. The next prime is 1212210847. The reversal of 1212210821 is 1280122121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1211736100 + 474721 = 34810^2 + 689^2 .

It is an emirp because it is prime and its reverse (1280122121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1212210821 - 2²² = 1208016517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1212210793 and 1212210802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1212210851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606105410 + 606105411.

It is an arithmetic number, because the mean of its divisors is an integer number (606105411).

Almost surely, 2^1212210821 is an apocalyptic number.

It is an amenable number.

1212210821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1212210821 is an equidigital number, since it uses as much as digits as its factorization.

1212210821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 1212210821 is about 34816.8180769007. The cubic root of 1212210821 is about 1066.2508379906.

Adding to 1212210821 its reverse (1280122121), we get a palindrome (2492332942).

The spelling of 1212210821 in words is "one billion, two hundred twelve million, two hundred ten thousand, eight hundred twenty-one".