1216015109 has 4 divisors (see below), whose sum is σ = 1216097100. Its totient is φ = 1215933120.

The previous prime is 1216015091. The next prime is 1216015111. The reversal of 1216015109 is 9015106121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9015106121 = 7 ⋅1287872303.

It can be written as a sum of positive squares in 2 ways, for example, as 870427009 + 345588100 = 29503^2 + 18590^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216015109 - 2¹⁶ = 1215949573 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 (1216015139) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11834 + ... + 50715.

It is an arithmetic number, because the mean of its divisors is an integer number (304024275).

Almost surely, 2^1216015109 is an apocalyptic number.

It is an amenable number.

1216015109 is a deficient number, since it is larger than the sum of its proper divisors (81991).

1216015109 is an equidigital number, since it uses as much as digits as its factorization.

1216015109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81990.

The product of its (nonzero) digits is 540, while the sum is 26.

The square root of 1216015109 is about 34871.4081877976. The cubic root of 1216015109 is about 1067.3650801811.

The spelling of 1216015109 in words is "one billion, two hundred sixteen million, fifteen thousand, one hundred nine".