1216505 has 4 divisors (see below), whose sum is σ = 1459812. Its totient is φ = 973200.

The previous prime is 1216489. The next prime is 1216507. The reversal of 1216505 is 5056121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 258064 + 958441 = 508^2 + 979^2 .

It is not a de Polignac number, because 1216505 - 2⁴ = 1216489 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216507) 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, 121646 + ... + 121655.

It is an arithmetic number, because the mean of its divisors is an integer number (364953).

2^1216505 is an apocalyptic number.

It is an amenable number.

1216505 is a deficient number, since it is larger than the sum of its proper divisors (243307).

1216505 is an equidigital number, since it uses as much as digits as its factorization.

1216505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243306.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 1216505 is about 1102.9528548401. The cubic root of 1216505 is about 106.7508395929.

The spelling of 1216505 in words is "one million, two hundred sixteen thousand, five hundred five".