1211209009 has 2 divisors, whose sum is σ = 1211209010. Its totient is φ = 1211209008.

The previous prime is 1211208991. The next prime is 1211209031. The reversal of 1211209009 is 9009021121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1209091984 + 2117025 = 34772^2 + 1455^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211209009 - 2⁷ = 1211208881 is a prime.

It is not a weakly prime, because it can be changed into another prime (1211209039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605604504 + 605604505.

It is an arithmetic number, because the mean of its divisors is an integer number (605604505).

Almost surely, 2^1211209009 is an apocalyptic number.

It is an amenable number.

1211209009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211209009 is an equidigital number, since it uses as much as digits as its factorization.

1211209009 is an evil number, because the sum of its binary digits is even.

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

The square root of 1211209009 is about 34802.4282055146. The cubic root of 1211209009 is about 1065.9570284590.

The spelling of 1211209009 in words is "one billion, two hundred eleven million, two hundred nine thousand, nine".