1216611641 has 6 divisors (see below), whose sum is σ = 1415242170. Its totient is φ = 1042809936.

The previous prime is 1216611637. The next prime is 1216611653. The reversal of 1216611641 is 1461166121.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1091641600 + 124970041 = 33040^2 + 11179^2 .

It is not a de Polignac number, because 1216611641 - 2² = 1216611637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216611631) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12414356 + ... + 12414453.

It is an arithmetic number, because the mean of its divisors is an integer number (235873695).

Almost surely, 2^1216611641 is an apocalyptic number.

It is an amenable number.

1216611641 is a deficient number, since it is larger than the sum of its proper divisors (198630529).

1216611641 is an equidigital number, since it uses as much as digits as its factorization.

1216611641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24828823 (or 24828816 counting only the distinct ones).

The product of its digits is 1728, while the sum is 29.

The square root of 1216611641 is about 34879.9604500923. The cubic root of 1216611641 is about 1067.5395882479.

Adding to 1216611641 its reverse (1461166121), we get a palindrome (2677777762).

The spelling of 1216611641 in words is "one billion, two hundred sixteen million, six hundred eleven thousand, six hundred forty-one".