1211012821 has 2 divisors, whose sum is σ = 1211012822. Its totient is φ = 1211012820.

The previous prime is 1211012807. The next prime is 1211013031. The reversal of 1211012821 is 1282101121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 671379921 + 539632900 = 25911^2 + 23230^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211012821 - 2¹⁵ = 1210980053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211012021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605506410 + 605506411.

It is an arithmetic number, because the mean of its divisors is an integer number (605506411).

Almost surely, 2^1211012821 is an apocalyptic number.

It is an amenable number.

1211012821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211012821 is an equidigital number, since it uses as much as digits as its factorization.

1211012821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 19.

The square root of 1211012821 is about 34799.6094949354. The cubic root of 1211012821 is about 1065.8994718446.

Adding to 1211012821 its reverse (1282101121), we get a palindrome (2493113942).

The spelling of 1211012821 in words is "one billion, two hundred eleven million, twelve thousand, eight hundred twenty-one".