1216005 has 32 divisors (see below), whose sum is σ = 2290944. Its totient is φ = 539136.

The previous prime is 1215923. The next prime is 1216009. The reversal of 1216005 is 5006121.

It is not a de Polignac number, because 1216005 - 2¹⁰ = 1214981 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216009) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3729 + ... + 4041.

It is an arithmetic number, because the mean of its divisors is an integer number (71592).

2^1216005 is an apocalyptic number.

1216005 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216005 is a deficient number, since it is larger than the sum of its proper divisors (1074939).

1216005 is a wasteful number, since it uses less digits than its factorization.

1216005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 1216005 is about 1102.7261672782. The cubic root of 1216005 is about 106.7362122426.

Adding to 1216005 its sum of digits (15), we get a triangular number (1216020 = T₁₅₅₉).

The spelling of 1216005 in words is "one million, two hundred sixteen thousand, five".