20505291 has 16 divisors (see below), whose sum is σ = 29199360. Its totient is φ = 12771360.

The previous prime is 20505269. The next prime is 20505307. The reversal of 20505291 is 19250502.

It is not a de Polignac number, because 20505291 - 2⁶ = 20505227 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20505241) 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 15 ways as a sum of consecutive naturals, for example, 1105 + ... + 6498.

It is an arithmetic number, because the mean of its divisors is an integer number (1824960).

Almost surely, 2^20505291 is an apocalyptic number.

20505291 is a deficient number, since it is larger than the sum of its proper divisors (8694069).

20505291 is a wasteful number, since it uses less digits than its factorization.

20505291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7666.

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 20505291 is about 4528.2768245769. The cubic root of 20505291 is about 273.7087275406.

Adding to 20505291 its reverse (19250502), we get a palindrome (39755793).

The spelling of 20505291 in words is "twenty million, five hundred five thousand, two hundred ninety-one".