20513503 has 4 divisors (see below), whose sum is σ = 21067960. Its totient is φ = 19959048.

The previous prime is 20513461. The next prime is 20513513. The reversal of 20513503 is 30531502.

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

It is a cyclic number.

It is not a de Polignac number, because 20513503 - 2⁹ = 20512991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20513513) 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 in 3 ways as a sum of consecutive naturals, for example, 277173 + ... + 277246.

It is an arithmetic number, because the mean of its divisors is an integer number (5266990).

Almost surely, 2^20513503 is an apocalyptic number.

20513503 is a deficient number, since it is larger than the sum of its proper divisors (554457).

20513503 is an equidigital number, since it uses as much as digits as its factorization.

20513503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554456.

The product of its (nonzero) digits is 450, while the sum is 19.

The square root of 20513503 is about 4529.1834804962. The cubic root of 20513503 is about 273.7452611372.

The spelling of 20513503 in words is "twenty million, five hundred thirteen thousand, five hundred three".