17921081 has 2 divisors, whose sum is σ = 17921082. Its totient is φ = 17921080.

The previous prime is 17921063. The next prime is 17921087. The reversal of 17921081 is 18012971.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12538681 + 5382400 = 3541^2 + 2320^2 .

It is an emirp because it is prime and its reverse (18012971) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 17921081 - 2²² = 13726777 is a prime.

It is a super-2 number, since 2×17921081² = 642330288417122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (17921087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8960540 + 8960541.

It is an arithmetic number, because the mean of its divisors is an integer number (8960541).

Almost surely, 2^17921081 is an apocalyptic number.

It is an amenable number.

17921081 is a deficient number, since it is larger than the sum of its proper divisors (1).

17921081 is an equidigital number, since it uses as much as digits as its factorization.

17921081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 17921081 is about 4233.3297769014. The cubic root of 17921081 is about 261.6905666478.

The spelling of 17921081 in words is "seventeen million, nine hundred twenty-one thousand, eighty-one".