1216555 has 4 divisors (see below), whose sum is σ = 1459872. Its totient is φ = 973240.

The previous prime is 1216547. The next prime is 1216559. The reversal of 1216555 is 5556121.

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

It is not a de Polignac number, because 1216555 - 2³ = 1216547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216559) 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, 121651 + ... + 121660.

It is an arithmetic number, because the mean of its divisors is an integer number (364968).

2^1216555 is an apocalyptic number.

1216555 is a deficient number, since it is larger than the sum of its proper divisors (243317).

1216555 is an equidigital number, since it uses as much as digits as its factorization.

1216555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243316.

The product of its digits is 1500, while the sum is 25.

The square root of 1216555 is about 1102.9755210339. The cubic root of 1216555 is about 106.7523021074.

It can be divided in two parts, 1216 and 555, that added together give a palindrome (1771).

The spelling of 1216555 in words is "one million, two hundred sixteen thousand, five hundred fifty-five".