1216561333 has 16 divisors (see below), whose sum is σ = 1369992960. Its totient is φ = 1071886464.

The previous prime is 1216561271. The next prime is 1216561349. The reversal of 1216561333 is 3331656121.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216561333 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1216561295 and 1216561304.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216561363) 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 15 ways as a sum of consecutive naturals, for example, 146353 + ... + 154441.

It is an arithmetic number, because the mean of its divisors is an integer number (85624560).

Almost surely, 2^1216561333 is an apocalyptic number.

1216561333 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1216561333 is a deficient number, since it is larger than the sum of its proper divisors (153431627).

1216561333 is a wasteful number, since it uses less digits than its factorization.

1216561333 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8628.

The product of its digits is 9720, while the sum is 31.

The square root of 1216561333 is about 34879.2392835624. The cubic root of 1216561333 is about 1067.5248734668.

The spelling of 1216561333 in words is "one billion, two hundred sixteen million, five hundred sixty-one thousand, three hundred thirty-three".