17661849421 has 2 divisors, whose sum is σ = 17661849422. Its totient is φ = 17661849420.

The previous prime is 17661849419. The next prime is 17661849451. The reversal of 17661849421 is 12494816671.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13277952900 + 4383896521 = 115230^2 + 66211^2 .

It is a cyclic number.

It is not a de Polignac number, because 17661849421 - 2¹ = 17661849419 is a prime.

Together with 17661849419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17661849451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8830924710 + 8830924711.

It is an arithmetic number, because the mean of its divisors is an integer number (8830924711).

Almost surely, 2^17661849421 is an apocalyptic number.

It is an amenable number.

17661849421 is a deficient number, since it is larger than the sum of its proper divisors (1).

17661849421 is an equidigital number, since it uses as much as digits as its factorization.

17661849421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 580608, while the sum is 49.

The spelling of 17661849421 in words is "seventeen billion, six hundred sixty-one million, eight hundred forty-nine thousand, four hundred twenty-one".