1216521307 has 2 divisors, whose sum is σ = 1216521308. Its totient is φ = 1216521306.

The previous prime is 1216521301. The next prime is 1216521337. The reversal of 1216521307 is 7031256121.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1216521307 is a prime.

It is not a weakly prime, because it can be changed into another prime (1216521301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608260653 + 608260654.

It is an arithmetic number, because the mean of its divisors is an integer number (608260654).

Almost surely, 2^1216521307 is an apocalyptic number.

1216521307 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216521307 is an equidigital number, since it uses as much as digits as its factorization.

1216521307 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 1216521307 is about 34878.6654991271. The cubic root of 1216521307 is about 1067.5131658178.

Adding to 1216521307 its reverse (7031256121), we get a palindrome (8247777428).

The spelling of 1216521307 in words is "one billion, two hundred sixteen million, five hundred twenty-one thousand, three hundred seven".