1217664691 has 2 divisors, whose sum is σ = 1217664692. Its totient is φ = 1217664690.

The previous prime is 1217664629. The next prime is 1217664727. The reversal of 1217664691 is 1964667121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1217664691 - 2¹⁵ = 1217631923 is a prime.

It is not a weakly prime, because it can be changed into another prime (1217664611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608832345 + 608832346.

It is an arithmetic number, because the mean of its divisors is an integer number (608832346).

Almost surely, 2^1217664691 is an apocalyptic number.

1217664691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1217664691 is an equidigital number, since it uses as much as digits as its factorization.

1217664691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

The square root of 1217664691 is about 34895.0525289761. The cubic root of 1217664691 is about 1067.8475058378.

It can be divided in two parts, 12176 and 64691, that added together give a palindrome (76867).

The spelling of 1217664691 in words is "one billion, two hundred seventeen million, six hundred sixty-four thousand, six hundred ninety-one".