20890305 has 20 divisors (see below), whose sum is σ = 37448532. Its totient is φ = 11141280.

The previous prime is 20890301. The next prime is 20890313. The reversal of 20890305 is 50309802.

It can be written as a sum of positive squares in 2 ways, for example, as 2537649 + 18352656 = 1593^2 + 4284^2 .

It is not a de Polignac number, because 20890305 - 2² = 20890301 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (20890301) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25386 + ... + 26195.

Almost surely, 2^20890305 is an apocalyptic number.

It is an amenable number.

20890305 is a deficient number, since it is larger than the sum of its proper divisors (16558227).

20890305 is an equidigital number, since it uses as much as digits as its factorization.

20890305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51598 (or 51589 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 20890305 is about 4570.5913184182. The cubic root of 20890305 is about 275.4111975170.

The spelling of 20890305 in words is "twenty million, eight hundred ninety thousand, three hundred five".