1216705109 has 4 divisors (see below), whose sum is σ = 1280742240. Its totient is φ = 1152667980.

The previous prime is 1216705097. The next prime is 1216705111. The reversal of 1216705109 is 9015076121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9015076121 = 2657 ⋅3392953.

It is a cyclic number.

It is not a de Polignac number, because 1216705109 - 2¹⁶ = 1216639573 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 (1216705169) 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 in 3 ways as a sum of consecutive naturals, for example, 32018537 + ... + 32018574.

It is an arithmetic number, because the mean of its divisors is an integer number (320185560).

Almost surely, 2^1216705109 is an apocalyptic number.

1216705109 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1216705109 is a deficient number, since it is larger than the sum of its proper divisors (64037131).

1216705109 is an equidigital number, since it uses as much as digits as its factorization.

1216705109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64037130.

The product of its (nonzero) digits is 3780, while the sum is 32.

The square root of 1216705109 is about 34881.3002767959. The cubic root of 1216705109 is about 1067.5669259870.

The spelling of 1216705109 in words is "one billion, two hundred sixteen million, seven hundred five thousand, one hundred nine".