17986821109 has 2 divisors, whose sum is σ = 17986821110. Its totient is φ = 17986821108.

The previous prime is 17986821107. The next prime is 17986821121. The reversal of 17986821109 is 90112868971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16336674225 + 1650146884 = 127815^2 + 40622^2 .

It is a cyclic number.

It is not a de Polignac number, because 17986821109 - 2¹ = 17986821107 is a prime.

Together with 17986821107, 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 (17986821101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8993410554 + 8993410555.

It is an arithmetic number, because the mean of its divisors is an integer number (8993410555).

Almost surely, 2^17986821109 is an apocalyptic number.

It is an amenable number.

17986821109 is a deficient number, since it is larger than the sum of its proper divisors (1).

17986821109 is an equidigital number, since it uses as much as digits as its factorization.

17986821109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 52.

The spelling of 17986821109 in words is "seventeen billion, nine hundred eighty-six million, eight hundred twenty-one thousand, one hundred nine".