19668321 has 6 divisors (see below), whose sum is σ = 28409810. Its totient is φ = 13112208.

The previous prime is 19668277. The next prime is 19668323. The reversal of 19668321 is 12386691.

It can be written as a sum of positive squares in only one way, i.e., 18792225 + 876096 = 4335^2 + 936^2 .

It is not a de Polignac number, because 19668321 - 2⁷ = 19668193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19668323) 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 in 5 ways as a sum of consecutive naturals, for example, 1092676 + ... + 1092693.

Almost surely, 2^19668321 is an apocalyptic number.

It is an amenable number.

19668321 is a deficient number, since it is larger than the sum of its proper divisors (8741489).

19668321 is a wasteful number, since it uses less digits than its factorization.

19668321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2185375 (or 2185372 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 19668321 is about 4434.8980822562. The cubic root of 19668321 is about 269.9328639663.

The spelling of 19668321 in words is "nineteen million, six hundred sixty-eight thousand, three hundred twenty-one".