20420871 has 4 divisors (see below), whose sum is σ = 27227832. Its totient is φ = 13613912.

The previous prime is 20420867. The next prime is 20420891. The reversal of 20420871 is 17802402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20420871 - 2² = 20420867 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20420821) 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 3 ways as a sum of consecutive naturals, for example, 3403476 + ... + 3403481.

It is an arithmetic number, because the mean of its divisors is an integer number (6806958).

Almost surely, 2^20420871 is an apocalyptic number.

20420871 is a deficient number, since it is larger than the sum of its proper divisors (6806961).

20420871 is an equidigital number, since it uses as much as digits as its factorization.

20420871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6806960.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20420871 is about 4518.9457841404. The cubic root of 20420871 is about 273.3325925355.

The spelling of 20420871 in words is "twenty million, four hundred twenty thousand, eight hundred seventy-one".