21023573 has 2 divisors, whose sum is σ = 21023574. Its totient is φ = 21023572.

The previous prime is 21023533. The next prime is 21023591. The reversal of 21023573 is 37532012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 293764 = 4553^2 + 542^2 .

It is a cyclic number.

It is not a de Polignac number, because 21023573 - 2²⁴ = 4246357 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 (21023503) 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, 10511786 + 10511787.

It is an arithmetic number, because the mean of its divisors is an integer number (10511787).

Almost surely, 2^21023573 is an apocalyptic number.

It is an amenable number.

21023573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21023573 is an equidigital number, since it uses as much as digits as its factorization.

21023573 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21023573 is about 4585.1469987341. The cubic root of 21023573 is about 275.9956109713.

Adding to 21023573 its reverse (37532012), we get a palindrome (58555585).

The spelling of 21023573 in words is "twenty-one million, twenty-three thousand, five hundred seventy-three".