1211218649 has 4 divisors (see below), whose sum is σ = 1213835136. Its totient is φ = 1208602164.

The previous prime is 1211218621. The next prime is 1211218651. The reversal of 1211218649 is 9468121121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9468121121 = 2161 ⋅4381361.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211218649 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1211218049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1307549 + ... + 1308474.

It is an arithmetic number, because the mean of its divisors is an integer number (303458784).

Almost surely, 2^1211218649 is an apocalyptic number.

It is an amenable number.

1211218649 is a deficient number, since it is larger than the sum of its proper divisors (2616487).

1211218649 is an equidigital number, since it uses as much as digits as its factorization.

1211218649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2616486.

The product of its digits is 6912, while the sum is 35.

The square root of 1211218649 is about 34802.5667013225. The cubic root of 1211218649 is about 1065.9598564319.

The spelling of 1211218649 in words is "one billion, two hundred eleven million, two hundred eighteen thousand, six hundred forty-nine".