20523421 has 2 divisors, whose sum is σ = 20523422. Its totient is φ = 20523420.

The previous prime is 20523407. The next prime is 20523431. The reversal of 20523421 is 12432502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12744900 + 7778521 = 3570^2 + 2789^2 .

It is a cyclic number.

It is not a de Polignac number, because 20523421 - 2¹¹ = 20521373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20523431) 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, 10261710 + 10261711.

It is an arithmetic number, because the mean of its divisors is an integer number (10261711).

Almost surely, 2^20523421 is an apocalyptic number.

It is an amenable number.

20523421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20523421 is an equidigital number, since it uses as much as digits as its factorization.

20523421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20523421 is about 4530.2782475252. The cubic root of 20523421 is about 273.7893714005.

Adding to 20523421 its reverse (12432502), we get a palindrome (32955923).

The spelling of 20523421 in words is "twenty million, five hundred twenty-three thousand, four hundred twenty-one".