1216645 has 8 divisors (see below), whose sum is σ = 1484280. Its totient is φ = 957120.

The previous prime is 1216619. The next prime is 1216681. The reversal of 1216645 is 5466121.

1216645 = T₁₁ + T₁₂ + ... + T₁₉₃.

It can be written as a sum of positive squares in 4 ways, for example, as 36 + 1216609 = 6^2 + 1103^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1216645 - 2¹⁵ = 1183877 is a prime.

It is an Ulam number.

1216645 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1690 + ... + 2299.

It is an arithmetic number, because the mean of its divisors is an integer number (185535).

2^1216645 is an apocalyptic number.

It is an amenable number.

1216645 is a deficient number, since it is larger than the sum of its proper divisors (267635).

1216645 is an equidigital number, since it uses as much as digits as its factorization.

1216645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4055.

The product of its digits is 1440, while the sum is 25.

The square root of 1216645 is about 1103.0163190089. The cubic root of 1216645 is about 106.7549345327.

The spelling of 1216645 in words is "one million, two hundred sixteen thousand, six hundred forty-five".