1221020011009 has 2 divisors, whose sum is σ = 1221020011010. Its totient is φ = 1221020011008.

The previous prime is 1221020011007. The next prime is 1221020011091. The reversal of 1221020011009 is 9001100201221.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 852445958400 + 368574052609 = 923280^2 + 607103^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221020011009 - 2¹ = 1221020011007 is a prime.

Together with 1221020011007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1221020011007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610510005504 + 610510005505.

It is an arithmetic number, because the mean of its divisors is an integer number (610510005505).

Almost surely, 2^{1221020011009} is an apocalyptic number.

It is an amenable number.

1221020011009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221020011009 is an equidigital number, since it uses as much as digits as its factorization.

1221020011009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 1221020011009 in words is "one trillion, two hundred twenty-one billion, twenty million, eleven thousand, nine".