1216921799 has 2 divisors, whose sum is σ = 1216921800. Its totient is φ = 1216921798.

The previous prime is 1216921793. The next prime is 1216921843. The reversal of 1216921799 is 9971296121.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1216921799 - 2¹² = 1216917703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216921793) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608460899 + 608460900.

It is an arithmetic number, because the mean of its divisors is an integer number (608460900).

Almost surely, 2^1216921799 is an apocalyptic number.

1216921799 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216921799 is an equidigital number, since it uses as much as digits as its factorization.

1216921799 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 1216921799 is about 34884.4062440512. The cubic root of 1216921799 is about 1067.6302985999.

The spelling of 1216921799 in words is "one billion, two hundred sixteen million, nine hundred twenty-one thousand, seven hundred ninety-nine".