1216312644 has 36 divisors (see below), whose sum is σ = 2878741712. Its totient is φ = 399707280.

The previous prime is 1216312637. The next prime is 1216312649. The reversal of 1216312644 is 4462136121.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (1216312649) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50439 + ... + 70545.

Almost surely, 2^1216312644 is an apocalyptic number.

It is an amenable number.

1216312644 is an abundant number, since it is smaller than the sum of its proper divisors (1662429068).

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

1216312644 is a wasteful number, since it uses less digits than its factorization.

1216312644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20256 (or 20183 counting only the distinct ones).

The product of its digits is 6912, while the sum is 30.

The square root of 1216312644 is about 34875.6741010120. The cubic root of 1216312644 is about 1067.4521275016.

Adding to 1216312644 its reverse (4462136121), we get a palindrome (5678448765).

The spelling of 1216312644 in words is "one billion, two hundred sixteen million, three hundred twelve thousand, six hundred forty-four".