20505090 has 16 divisors (see below), whose sum is σ = 49212288. Its totient is φ = 5468016.

The previous prime is 20505083. The next prime is 20505091. The reversal of 20505090 is 9050502.

It is not an unprimeable number, because it can be changed into a prime (20505091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 341722 + ... + 341781.

It is an arithmetic number, because the mean of its divisors is an integer number (3075768).

Almost surely, 2^20505090 is an apocalyptic number.

20505090 is an abundant number, since it is smaller than the sum of its proper divisors (28707198).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20505090 is a wasteful number, since it uses less digits than its factorization.

20505090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 683513.

The product of its (nonzero) digits is 450, while the sum is 21.

The square root of 20505090 is about 4528.2546306497. The cubic root of 20505090 is about 273.7078332083.

Adding to 20505090 its reverse (9050502), we get a palindrome (29555592).

It can be divided in two parts, 2050 and 5090, that added together give a triangular number (7140 = T₁₁₉).

The spelling of 20505090 in words is "twenty million, five hundred five thousand, ninety".