21172003 has 2 divisors, whose sum is σ = 21172004. Its totient is φ = 21172002.

The previous prime is 21171991. The next prime is 21172009. The reversal of 21172003 is 30027112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21172003 - 2¹⁷ = 21040931 is a prime.

It is a super-2 number, since 2×21172003² = 896507422064018, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21172009) 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, 10586001 + 10586002.

It is an arithmetic number, because the mean of its divisors is an integer number (10586002).

Almost surely, 2^21172003 is an apocalyptic number.

21172003 is a deficient number, since it is larger than the sum of its proper divisors (1).

21172003 is an equidigital number, since it uses as much as digits as its factorization.

21172003 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21172003 is about 4601.3044889466. The cubic root of 21172003 is about 276.6436136660.

Adding to 21172003 its reverse (30027112), we get a palindrome (51199115).

The spelling of 21172003 in words is "twenty-one million, one hundred seventy-two thousand, three".