20645321 has 2 divisors, whose sum is σ = 20645322. Its totient is φ = 20645320.

The previous prime is 20645311. The next prime is 20645341. The reversal of 20645321 is 12354602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17547721 + 3097600 = 4189^2 + 1760^2 .

It is a cyclic number.

It is not a de Polignac number, because 20645321 - 2⁶ = 20645257 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20645311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10322660 + 10322661.

It is an arithmetic number, because the mean of its divisors is an integer number (10322661).

Almost surely, 2^20645321 is an apocalyptic number.

It is an amenable number.

20645321 is a deficient number, since it is larger than the sum of its proper divisors (1).

20645321 is an equidigital number, since it uses as much as digits as its factorization.

20645321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 20645321 is about 4543.7122488115. The cubic root of 20645321 is about 274.3303641221.

Adding to 20645321 its reverse (12354602), we get a palindrome (32999923).

The spelling of 20645321 in words is "twenty million, six hundred forty-five thousand, three hundred twenty-one".