20420705 has 4 divisors (see below), whose sum is σ = 24504852. Its totient is φ = 16336560.

The previous prime is 20420681. The next prime is 20420759. The reversal of 20420705 is 50702402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50702402 = 2 ⋅25351201.

It can be written as a sum of positive squares in 2 ways, for example, as 8976016 + 11444689 = 2996^2 + 3383^2 .

It is not a de Polignac number, because 20420705 - 2¹⁸ = 20158561 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, 2042066 + ... + 2042075.

It is an arithmetic number, because the mean of its divisors is an integer number (6126213).

Almost surely, 2^20420705 is an apocalyptic number.

It is an amenable number.

20420705 is a deficient number, since it is larger than the sum of its proper divisors (4084147).

20420705 is an equidigital number, since it uses as much as digits as its factorization.

20420705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4084146.

The product of its (nonzero) digits is 560, while the sum is 20.

The square root of 20420705 is about 4518.9274169874. The cubic root of 20420705 is about 273.3318518989.

The spelling of 20420705 in words is "twenty million, four hundred twenty thousand, seven hundred five".