16403021 has 2 divisors, whose sum is σ = 16403022. Its totient is φ = 16403020.

The previous prime is 16403017. The next prime is 16403039. The reversal of 16403021 is 12030461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13213225 + 3189796 = 3635^2 + 1786^2 .

It is an emirp because it is prime and its reverse (12030461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16403021 - 2² = 16403017 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16483021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8201510 + 8201511.

It is an arithmetic number, because the mean of its divisors is an integer number (8201511).

Almost surely, 2^16403021 is an apocalyptic number.

It is an amenable number.

16403021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16403021 is an equidigital number, since it uses as much as digits as its factorization.

16403021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 16403021 is about 4050.0643204769. The cubic root of 16403021 is about 254.0824179190.

Adding to 16403021 its reverse (12030461), we get a palindrome (28433482).

The spelling of 16403021 in words is "sixteen million, four hundred three thousand, twenty-one".