1216564549 has 2 divisors, whose sum is σ = 1216564550. Its totient is φ = 1216564548.

The previous prime is 1216564519. The next prime is 1216564567. The reversal of 1216564549 is 9454656121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 868480900 + 348083649 = 29470^2 + 18657^2 .

It is an emirp because it is prime and its reverse (9454656121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1216564549 - 2²⁵ = 1183010117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216564519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608282274 + 608282275.

It is an arithmetic number, because the mean of its divisors is an integer number (608282275).

Almost surely, 2^1216564549 is an apocalyptic number.

It is an amenable number.

1216564549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216564549 is an equidigital number, since it uses as much as digits as its factorization.

1216564549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 43.

The square root of 1216564549 is about 34879.2853854548. The cubic root of 1216564549 is about 1067.5258141392.

The spelling of 1216564549 in words is "one billion, two hundred sixteen million, five hundred sixty-four thousand, five hundred forty-nine".