21026573 has 2 divisors, whose sum is σ = 21026574. Its totient is φ = 21026572.

The previous prime is 21026567. The next prime is 21026581. The reversal of 21026573 is 37562012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 114244 = 4573^2 + 338^2 .

It is a cyclic number.

It is not a de Polignac number, because 21026573 - 2⁴ = 21026557 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 (21023573) 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, 10513286 + 10513287.

It is an arithmetic number, because the mean of its divisors is an integer number (10513287).

Almost surely, 2^21026573 is an apocalyptic number.

It is an amenable number.

21026573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21026573 is an equidigital number, since it uses as much as digits as its factorization.

21026573 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21026573 is about 4585.4741303381. The cubic root of 21026573 is about 276.0087382587.

Adding to 21026573 its reverse (37562012), we get a palindrome (58588585).

The spelling of 21026573 in words is "twenty-one million, twenty-six thousand, five hundred seventy-three".