1216112509 has 4 divisors (see below), whose sum is σ = 1219617504. Its totient is φ = 1212607516.

The previous prime is 1216112501. The next prime is 1216112533. The reversal of 1216112509 is 9052116121.

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.

It is a cyclic number.

It is not a de Polignac number, because 1216112509 - 2³ = 1216112501 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 (1216112501) 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, 1751977 + ... + 1752670.

It is an arithmetic number, because the mean of its divisors is an integer number (304904376).

Almost surely, 2^1216112509 is an apocalyptic number.

It is an amenable number.

1216112509 is a deficient number, since it is larger than the sum of its proper divisors (3504995).

1216112509 is an equidigital number, since it uses as much as digits as its factorization.

1216112509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3504994.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 1216112509 is about 34872.8047194372. The cubic root of 1216112509 is about 1067.3935772456.

The spelling of 1216112509 in words is "one billion, two hundred sixteen million, one hundred twelve thousand, five hundred nine".