20421085 has 4 divisors (see below), whose sum is σ = 24505308. Its totient is φ = 16336864.

The previous prime is 20421073. The next prime is 20421103. The reversal of 20421085 is 58012402.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5257849 + 15163236 = 2293^2 + 3894^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421085 - 2⁷ = 20420957 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent 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, 2042104 + ... + 2042113.

It is an arithmetic number, because the mean of its divisors is an integer number (6126327).

Almost surely, 2^20421085 is an apocalyptic number.

It is an amenable number.

20421085 is a deficient number, since it is larger than the sum of its proper divisors (4084223).

20421085 is an equidigital number, since it uses as much as digits as its factorization.

20421085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4084222.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 20421085 is about 4518.9694621672. The cubic root of 20421085 is about 273.3335473262. Note that the first 3 decimals are identical.

Adding to 20421085 its reverse (58012402), we get a palindrome (78433487).

The spelling of 20421085 in words is "twenty million, four hundred twenty-one thousand, eighty-five".