1216606591 has 2 divisors, whose sum is σ = 1216606592. Its totient is φ = 1216606590.

The previous prime is 1216606577. The next prime is 1216606639. The reversal of 1216606591 is 1956066121.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1216606591 - 2¹³ = 1216598399 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1216606591.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216606541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608303295 + 608303296.

It is an arithmetic number, because the mean of its divisors is an integer number (608303296).

Almost surely, 2^1216606591 is an apocalyptic number.

1216606591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216606591 is an equidigital number, since it uses as much as digits as its factorization.

1216606591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 1216606591 is about 34879.8880588800. Note that the first 3 decimals coincide. The cubic root of 1216606591 is about 1067.5381111722.

The spelling of 1216606591 in words is "one billion, two hundred sixteen million, six hundred six thousand, five hundred ninety-one".