20500021 has 8 divisors (see below), whose sum is σ = 21296384. Its totient is φ = 19712160.

The previous prime is 20500019. The next prime is 20500027. The reversal of 20500021 is 12000502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20500021 - 2¹ = 20500019 is a prime.

It is a super-2 number, since 2×20500021² = 840501722000882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20499980 and 20500007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20500027) 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 7 ways as a sum of consecutive naturals, for example, 3025 + ... + 7081.

It is an arithmetic number, because the mean of its divisors is an integer number (2662048).

Almost surely, 2^20500021 is an apocalyptic number.

It is an amenable number.

20500021 is a deficient number, since it is larger than the sum of its proper divisors (796363).

20500021 is a wasteful number, since it uses less digits than its factorization.

20500021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4251.

The product of its (nonzero) digits is 20, while the sum is 10.

The square root of 20500021 is about 4527.6948881302. The cubic root of 20500021 is about 273.6852771934.

Adding to 20500021 its reverse (12000502), we get a palindrome (32500523).

The spelling of 20500021 in words is "twenty million, five hundred thousand, twenty-one".