1216639 has 8 divisors (see below), whose sum is σ = 1311120. Its totient is φ = 1124736.

The previous prime is 1216619. The next prime is 1216681. The reversal of 1216639 is 9366121.

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

It is a cyclic number.

It is not a de Polignac number, because 1216639 - 2¹³ = 1208447 is a prime.

It is a Duffinian number.

1216639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 397 + ... + 1609.

It is an arithmetic number, because the mean of its divisors is an integer number (163890).

2^1216639 is an apocalyptic number.

1216639 is a deficient number, since it is larger than the sum of its proper divisors (94481).

1216639 is a wasteful number, since it uses less digits than its factorization.

1216639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1289.

The product of its digits is 1944, while the sum is 28.

The square root of 1216639 is about 1103.0135991909. The cubic root of 1216639 is about 106.7547590417.

It can be divided in two parts, 12166 and 39, that multiplied together give a palindrome (474474).

The spelling of 1216639 in words is "one million, two hundred sixteen thousand, six hundred thirty-nine".