1216979643 has 18 divisors (see below), whose sum is σ = 1784537076. Its totient is φ = 737160600.

The previous prime is 1216979641. The next prime is 1216979653. The reversal of 1216979643 is 3469796121.

It is not a de Polignac number, because 1216979643 - 2¹ = 1216979641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1216979592 and 1216979601.

It is not an unprimeable number, because it can be changed into a prime (1216979641) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 663738 + ... + 665568.

Almost surely, 2^1216979643 is an apocalyptic number.

1216979643 is a deficient number, since it is larger than the sum of its proper divisors (567557433).

1216979643 is an frugal number, since it uses more digits than its factorization.

1216979643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3687 (or 1845 counting only the distinct ones).

The product of its digits is 489888, while the sum is 48.

The square root of 1216979643 is about 34885.2353152448. The cubic root of 1216979643 is about 1067.6472142386.

Multiplying 1216979643 by its sum of digits (48), we get a square (58415022864 = 241692²).

The spelling of 1216979643 in words is "one billion, two hundred sixteen million, nine hundred seventy-nine thousand, six hundred forty-three".