1216817841 has 4 divisors (see below), whose sum is σ = 1622423792. Its totient is φ = 811211892.

The previous prime is 1216817759. The next prime is 1216817869. The reversal of 1216817841 is 1487186121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1487186121 = 3 ⋅495728707.

It is not a de Polignac number, because 1216817841 - 2¹¹ = 1216815793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1216817841.

It is not an unprimeable number, because it can be changed into a prime (1216817341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 202802971 + ... + 202802976.

It is an arithmetic number, because the mean of its divisors is an integer number (405605948).

Almost surely, 2^1216817841 is an apocalyptic number.

It is an amenable number.

1216817841 is a deficient number, since it is larger than the sum of its proper divisors (405605951).

1216817841 is an equidigital number, since it uses as much as digits as its factorization.

1216817841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405605950.

The product of its digits is 21504, while the sum is 39.

The square root of 1216817841 is about 34882.9161768336. The cubic root of 1216817841 is about 1067.5998962434.

The spelling of 1216817841 in words is "one billion, two hundred sixteen million, eight hundred seventeen thousand, eight hundred forty-one".