1216732991 has 2 divisors, whose sum is σ = 1216732992. Its totient is φ = 1216732990.

The previous prime is 1216732969. The next prime is 1216733041. The reversal of 1216732991 is 1992376121.

It is a weak prime.

It is an emirp because it is prime and its reverse (1992376121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1216732991 - 2¹⁴ = 1216716607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216732921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608366495 + 608366496.

It is an arithmetic number, because the mean of its divisors is an integer number (608366496).

Almost surely, 2^1216732991 is an apocalyptic number.

1216732991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216732991 is an equidigital number, since it uses as much as digits as its factorization.

1216732991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 41.

The square root of 1216732991 is about 34881.6999442401. The cubic root of 1216732991 is about 1067.5750807085.

The spelling of 1216732991 in words is "one billion, two hundred sixteen million, seven hundred thirty-two thousand, nine hundred ninety-one".