20505505 has 4 divisors (see below), whose sum is σ = 24606612. Its totient is φ = 16404400.

The previous prime is 20505497. The next prime is 20505571. The reversal of 20505505 is 50550502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50550502 = 2 ⋅25275251.

It can be written as a sum of positive squares in 2 ways, for example, as 11209104 + 9296401 = 3348^2 + 3049^2 .

It is not a de Polignac number, because 20505505 - 2³ = 20505497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2050546 + ... + 2050555.

It is an arithmetic number, because the mean of its divisors is an integer number (6151653).

Almost surely, 2^20505505 is an apocalyptic number.

It is an amenable number.

20505505 is a deficient number, since it is larger than the sum of its proper divisors (4101107).

20505505 is an equidigital number, since it uses as much as digits as its factorization.

20505505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4101106.

The product of its (nonzero) digits is 1250, while the sum is 22.

The square root of 20505505 is about 4528.3004538127. The cubic root of 20505505 is about 273.7096797089.

The spelling of 20505505 in words is "twenty million, five hundred five thousand, five hundred five".