1216305 has 24 divisors (see below), whose sum is σ = 2134080. Its totient is φ = 640800.

The previous prime is 1216277. The next prime is 1216337. The reversal of 1216305 is 5036121.

1216305 = T₁₅ + T₁₆ + ... + T₁₉₃.

It is not a de Polignac number, because 1216305 - 2⁵ = 1216273 is a prime.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6706 + ... + 6884.

It is an arithmetic number, because the mean of its divisors is an integer number (88920).

2^1216305 is an apocalyptic number.

1216305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216305 is a deficient number, since it is larger than the sum of its proper divisors (917775).

1216305 is a wasteful number, since it uses less digits than its factorization.

1216305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 1216305 is about 1102.8621854067. The cubic root of 1216305 is about 106.7449891338.

It can be divided in two parts, 1216 and 305, that added together give a square (1521 = 39²).

The spelling of 1216305 in words is "one million, two hundred sixteen thousand, three hundred five".