21003473 has 2 divisors, whose sum is σ = 21003474. Its totient is φ = 21003472.

The previous prime is 21003431. The next prime is 21003491. The reversal of 21003473 is 37430012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19775809 + 1227664 = 4447^2 + 1108^2 .

It is a cyclic number.

It is not a de Polignac number, because 21003473 - 2¹⁴ = 20987089 is a prime.

It is a super-2 number, since 2×21003473² = 882291756123458, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21003413) 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, 10501736 + 10501737.

It is an arithmetic number, because the mean of its divisors is an integer number (10501737).

Almost surely, 2^21003473 is an apocalyptic number.

It is an amenable number.

21003473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003473 is an equidigital number, since it uses as much as digits as its factorization.

21003473 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 21003473 is about 4582.9546146564. The cubic root of 21003473 is about 275.9076259167.

Adding to 21003473 its reverse (37430012), we get a palindrome (58433485).

The spelling of 21003473 in words is "twenty-one million, three thousand, four hundred seventy-three".