20639903 has 2 divisors, whose sum is σ = 20639904. Its totient is φ = 20639902.

The previous prime is 20639897. The next prime is 20639923. The reversal of 20639903 is 30993602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20639903 - 2¹⁸ = 20377759 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20639903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20639923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10319951 + 10319952.

It is an arithmetic number, because the mean of its divisors is an integer number (10319952).

Almost surely, 2^20639903 is an apocalyptic number.

20639903 is a deficient number, since it is larger than the sum of its proper divisors (1).

20639903 is an equidigital number, since it uses as much as digits as its factorization.

20639903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 32.

The square root of 20639903 is about 4543.1160011604. The cubic root of 20639903 is about 274.3063643023.

The spelling of 20639903 in words is "twenty million, six hundred thirty-nine thousand, nine hundred three".