20003021 has 4 divisors (see below), whose sum is σ = 20032992. Its totient is φ = 19973052.

The previous prime is 20003003. The next prime is 20003023. The reversal of 20003021 is 12030002.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20003021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20003023) 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, 13961 + ... + 15326.

It is an arithmetic number, because the mean of its divisors is an integer number (5008248).

Almost surely, 2^20003021 is an apocalyptic number.

It is an amenable number.

20003021 is a deficient number, since it is larger than the sum of its proper divisors (29971).

20003021 is an equidigital number, since it uses as much as digits as its factorization.

20003021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29970.

The product of its (nonzero) digits is 12, while the sum is 8.

The square root of 20003021 is about 4472.4737003140. The cubic root of 20003021 is about 271.4554280641.

Adding to 20003021 its reverse (12030002), we get a palindrome (32033023).

The spelling of 20003021 in words is "twenty million, three thousand, twenty-one".