20505603 has 4 divisors (see below), whose sum is σ = 27340808. Its totient is φ = 13670400.

The previous prime is 20505599. The next prime is 20505619. The reversal of 20505603 is 30650502.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20505603 - 2² = 20505599 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20505603.

It is not an unprimeable number, because it can be changed into a prime (20505623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3417598 + ... + 3417603.

It is an arithmetic number, because the mean of its divisors is an integer number (6835202).

Almost surely, 2^20505603 is an apocalyptic number.

20505603 is a deficient number, since it is larger than the sum of its proper divisors (6835205).

20505603 is an equidigital number, since it uses as much as digits as its factorization.

20505603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6835204.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 20505603 is about 4528.3112746365. The cubic root of 20505603 is about 273.7101157464.

The spelling of 20505603 in words is "twenty million, five hundred five thousand, six hundred three".