1216542321 has 48 divisors (see below), whose sum is σ = 1938081600. Its totient is φ = 762571584.

The previous prime is 1216542319. The next prime is 1216542361. The reversal of 1216542321 is 1232456121.

1216542321 is a `hidden beast` number, since 1 + 2 + 1 + 654 + 2 + 3 + 2 + 1 = 666.

It is not a de Polignac number, because 1216542321 - 2¹ = 1216542319 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1216542361) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1193350 + ... + 1194368.

It is an arithmetic number, because the mean of its divisors is an integer number (40376700).

Almost surely, 2^1216542321 is an apocalyptic number.

It is an amenable number.

1216542321 is a deficient number, since it is larger than the sum of its proper divisors (721539279).

1216542321 is an frugal number, since it uses more digits than its factorization.

1216542321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085 (or 1039 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 1216542321 is about 34878.9667421499. The cubic root of 1216542321 is about 1067.5193124679.

Adding to 1216542321 its reverse (1232456121), we get a palindrome (2448998442).

The spelling of 1216542321 in words is "one billion, two hundred sixteen million, five hundred forty-two thousand, three hundred twenty-one".