1211780663 has 4 divisors (see below), whose sum is σ = 1212324600. Its totient is φ = 1211236728.

The previous prime is 1211780629. The next prime is 1211780681. The reversal of 1211780663 is 3660871121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3660871121 = 683 ⋅5359987.

It is a cyclic number.

It is not a de Polignac number, because 1211780663 - 2¹⁸ = 1211518519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211780963) 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, 268613 + ... + 273086.

It is an arithmetic number, because the mean of its divisors is an integer number (303081150).

Almost surely, 2^1211780663 is an apocalyptic number.

1211780663 is a deficient number, since it is larger than the sum of its proper divisors (543937).

1211780663 is an equidigital number, since it uses as much as digits as its factorization.

1211780663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543936.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 1211780663 is about 34810.6400831700. The cubic root of 1211780663 is about 1066.1247019031.

The spelling of 1211780663 in words is "one billion, two hundred eleven million, seven hundred eighty thousand, six hundred sixty-three".