17991641 has 2 divisors, whose sum is σ = 17991642. Its totient is φ = 17991640.

The previous prime is 17991599. The next prime is 17991679. The reversal of 17991641 is 14619971.

It is an a-pointer prime, because the next prime (17991679) can be obtained adding 17991641 to its sum of digits (38).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15523600 + 2468041 = 3940^2 + 1571^2 .

It is a cyclic number.

It is not a de Polignac number, because 17991641 - 2¹⁸ = 17729497 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 17991595 and 17991604.

It is not a weakly prime, because it can be changed into another prime (17991691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8995820 + 8995821.

It is an arithmetic number, because the mean of its divisors is an integer number (8995821).

Almost surely, 2^17991641 is an apocalyptic number.

It is an amenable number.

17991641 is a deficient number, since it is larger than the sum of its proper divisors (1).

17991641 is an equidigital number, since it uses as much as digits as its factorization.

17991641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 38.

The square root of 17991641 is about 4241.6554551260. The cubic root of 17991641 is about 262.0335650333.

The spelling of 17991641 in words is "seventeen million, nine hundred ninety-one thousand, six hundred forty-one".