1216664656 has 10 divisors (see below), whose sum is σ = 2357287802. Its totient is φ = 608332320.

The previous prime is 1216664629. The next prime is 1216664671. The reversal of 1216664656 is 6564666121.

It can be written as a sum of positive squares in only one way, i.e., 1196053056 + 20611600 = 34584^2 + 4540^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38020755 + ... + 38020786.

Almost surely, 2^1216664656 is an apocalyptic number.

1216664656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1216664656 is a deficient number, since it is larger than the sum of its proper divisors (1140623146).

1216664656 is an equidigital number, since it uses as much as digits as its factorization.

1216664656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76041549 (or 76041543 counting only the distinct ones).

The product of its digits is 311040, while the sum is 43.

The square root of 1216664656 is about 34880.7204054045. The cubic root of 1216664656 is about 1067.5550943709. Note that the first 3 decimals are identical.

The spelling of 1216664656 in words is "one billion, two hundred sixteen million, six hundred sixty-four thousand, six hundred fifty-six".