1216605656 has 16 divisors (see below), whose sum is σ = 2607012240. Its totient is φ = 521402400.

The previous prime is 1216605653. The next prime is 1216605671. The reversal of 1216605656 is 6565066121.

It is a super-2 number, since 2×1216605656² = 2960258644422380672, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216605653) 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, 10862495 + ... + 10862606.

It is an arithmetic number, because the mean of its divisors is an integer number (162938265).

Almost surely, 2^1216605656 is an apocalyptic number.

It is an amenable number.

1216605656 is an abundant number, since it is smaller than the sum of its proper divisors (1390406584).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1216605656 is a wasteful number, since it uses less digits than its factorization.

1216605656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21725114 (or 21725110 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 1216605656 is about 34879.8746557381. The cubic root of 1216605656 is about 1067.5378376934.

The spelling of 1216605656 in words is "one billion, two hundred sixteen million, six hundred five thousand, six hundred fifty-six".