1216111505 has 16 divisors (see below), whose sum is σ = 1668501120. Its totient is φ = 833559552.

The previous prime is 1216111489. The next prime is 1216111513. The reversal of 1216111505 is 5051116121.

It is not a de Polignac number, because 1216111505 - 2⁴ = 1216111489 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101681 + ... + 113009.

It is an arithmetic number, because the mean of its divisors is an integer number (104281320).

Almost surely, 2^1216111505 is an apocalyptic number.

It is an amenable number.

1216111505 is a deficient number, since it is larger than the sum of its proper divisors (452389615).

1216111505 is a wasteful number, since it uses less digits than its factorization.

1216111505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14408.

The product of its (nonzero) digits is 300, while the sum is 23.

The square root of 1216111505 is about 34872.7903242628. The cubic root of 1216111505 is about 1067.3932835054.

Adding to 1216111505 its reverse (5051116121), we get a palindrome (6267227626).

The spelling of 1216111505 in words is "one billion, two hundred sixteen million, one hundred eleven thousand, five hundred five".