20640001 has 2 divisors, whose sum is σ = 20640002. Its totient is φ = 20640000.

The previous prime is 20639959. The next prime is 20640007. The reversal of 20640001 is 10004602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19793601 + 846400 = 4449^2 + 920^2 .

It is a cyclic number.

It is not a de Polignac number, because 20640001 - 2¹⁹ = 20115713 is a prime.

It is not a weakly prime, because it can be changed into another prime (20640007) 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, 10320000 + 10320001.

It is an arithmetic number, because the mean of its divisors is an integer number (10320001).

Almost surely, 2^20640001 is an apocalyptic number.

It is an amenable number.

20640001 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640001 is an equidigital number, since it uses as much as digits as its factorization.

20640001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 20640001 is about 4543.1267866966. The cubic root of 20640001 is about 274.3067984449.

Adding to 20640001 its reverse (10004602), we get a palindrome (30644603).

The spelling of 20640001 in words is "twenty million, six hundred forty thousand, one".