20505513 has 8 divisors (see below), whose sum is σ = 31246528. Its totient is φ = 11717424.

The previous prime is 20505497. The next prime is 20505571. The reversal of 20505513 is 31550502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20505513 - 2⁴ = 20505497 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 976453 = 20505513 / (2 + 0 + 5 + 0 + 5 + 5 + 1 + 3).

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 20505513.

It is not an unprimeable number, because it can be changed into a prime (20505593) 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 7 ways as a sum of consecutive naturals, for example, 488206 + ... + 488247.

It is an arithmetic number, because the mean of its divisors is an integer number (3905816).

Almost surely, 2^20505513 is an apocalyptic number.

It is an amenable number.

20505513 is a deficient number, since it is larger than the sum of its proper divisors (10741015).

20505513 is an equidigital number, since it uses as much as digits as its factorization.

20505513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 976463.

The product of its (nonzero) digits is 750, while the sum is 21.

The square root of 20505513 is about 4528.3013371462. The cubic root of 20505513 is about 273.7097153039.

The spelling of 20505513 in words is "twenty million, five hundred five thousand, five hundred thirteen".