1216081816 has 8 divisors (see below), whose sum is σ = 2280153420. Its totient is φ = 608040904.

The previous prime is 1216081813. The next prime is 1216081817. The reversal of 1216081816 is 6181806121.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216081813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 76005106 + ... + 76005121.

Almost surely, 2^1216081816 is an apocalyptic number.

It is an amenable number.

1216081816 is a deficient number, since it is larger than the sum of its proper divisors (1064071604).

1216081816 is a wasteful number, since it uses less digits than its factorization.

1216081816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152010233 (or 152010229 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 34.

The square root of 1216081816 is about 34872.3646459485. The cubic root of 1216081816 is about 1067.3845973235.

Adding to 1216081816 its reverse (6181806121), we get a palindrome (7397887937).

The spelling of 1216081816 in words is "one billion, two hundred sixteen million, eighty-one thousand, eight hundred sixteen".