1216215656 has 8 divisors (see below), whose sum is σ = 2280404370. Its totient is φ = 608107824.

The previous prime is 1216215619. The next prime is 1216215661. The reversal of 1216215656 is 6565126121.

It can be written as a sum of positive squares in only one way, i.e., 981819556 + 234396100 = 31334^2 + 15310^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 76013471 + ... + 76013486.

Almost surely, 2^1216215656 is an apocalyptic number.

It is an amenable number.

1216215656 is a deficient number, since it is larger than the sum of its proper divisors (1064188714).

1216215656 is a wasteful number, since it uses less digits than its factorization.

1216215656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152026963 (or 152026959 counting only the distinct ones).

The product of its digits is 21600, while the sum is 35.

The square root of 1216215656 is about 34874.2835912080. The cubic root of 1216215656 is about 1067.4237540952.

The spelling of 1216215656 in words is "one billion, two hundred sixteen million, two hundred fifteen thousand, six hundred fifty-six".