1216964221 has 4 divisors (see below), whose sum is σ = 1327597344. Its totient is φ = 1106331100.

The previous prime is 1216964219. The next prime is 1216964263. The reversal of 1216964221 is 1224696121.

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: 1224696121 = 11 ⋅111336011.

It is a cyclic number.

It is not a de Polignac number, because 1216964221 - 2¹ = 1216964219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216965221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55316545 + ... + 55316566.

It is an arithmetic number, because the mean of its divisors is an integer number (331899336).

Almost surely, 2^1216964221 is an apocalyptic number.

1216964221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1216964221 is a deficient number, since it is larger than the sum of its proper divisors (110633123).

1216964221 is a wasteful number, since it uses less digits than its factorization.

1216964221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110633122.

The product of its digits is 10368, while the sum is 34.

The square root of 1216964221 is about 34885.0142754736. The cubic root of 1216964221 is about 1067.6427043508.

The spelling of 1216964221 in words is "one billion, two hundred sixteen million, nine hundred sixty-four thousand, two hundred twenty-one".