20200021 has 4 divisors (see below), whose sum is σ = 21263200. Its totient is φ = 19136844.

The previous prime is 20200013. The next prime is 20200027. The reversal of 20200021 is 12000202.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12000202 = 2 ⋅6000101.

It is a cyclic number.

It is not a de Polignac number, because 20200021 - 2³ = 20200013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20199977 and 20200013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20200027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 531561 + ... + 531598.

It is an arithmetic number, because the mean of its divisors is an integer number (5315800).

Almost surely, 2^20200021 is an apocalyptic number.

It is an amenable number.

20200021 is a deficient number, since it is larger than the sum of its proper divisors (1063179).

20200021 is a wasteful number, since it uses less digits than its factorization.

20200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1063178.

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 20200021 is about 4494.4433470676. The cubic root of 20200021 is about 272.3436625333.

Adding to 20200021 its reverse (12000202), we get a palindrome (32200223).

The spelling of 20200021 in words is "twenty million, two hundred thousand, twenty-one".