1209921001 has 2 divisors, whose sum is σ = 1209921002. Its totient is φ = 1209921000.

The previous prime is 1209920993. The next prime is 1209921017. The reversal of 1209921001 is 1001299021.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1001089600 + 208831401 = 31640^2 + 14451^2 .

It is a cyclic number.

It is not a de Polignac number, because 1209921001 - 2³ = 1209920993 is a prime.

It is not a weakly prime, because it can be changed into another prime (1209921101) 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, 604960500 + 604960501.

It is an arithmetic number, because the mean of its divisors is an integer number (604960501).

Almost surely, 2^1209921001 is an apocalyptic number.

It is an amenable number.

1209921001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1209921001 is an equidigital number, since it uses as much as digits as its factorization.

1209921001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 1209921001 is about 34783.9187125315. The cubic root of 1209921001 is about 1065.5790457630.

The spelling of 1209921001 in words is "one billion, two hundred nine million, nine hundred twenty-one thousand, one".