1216521337 has 2 divisors, whose sum is σ = 1216521338. Its totient is φ = 1216521336.

The previous prime is 1216521307. The next prime is 1216521403. The reversal of 1216521337 is 7331256121.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 774008041 + 442513296 = 27821^2 + 21036^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216521337 - 2¹⁵ = 1216488569 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1216521299 and 1216521308.

It is not a weakly prime, because it can be changed into another prime (1216521307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608260668 + 608260669.

It is an arithmetic number, because the mean of its divisors is an integer number (608260669).

Almost surely, 2^1216521337 is an apocalyptic number.

It is an amenable number.

1216521337 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216521337 is an equidigital number, since it uses as much as digits as its factorization.

1216521337 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 31.

The square root of 1216521337 is about 34878.6659291894. The cubic root of 1216521337 is about 1067.5131745929.

Adding to 1216521337 its reverse (7331256121), we get a palindrome (8547777458).

The spelling of 1216521337 in words is "one billion, two hundred sixteen million, five hundred twenty-one thousand, three hundred thirty-seven".