20403021 has 16 divisors (see below), whose sum is σ = 28070144. Its totient is φ = 13172544.

The previous prime is 20403013. The next prime is 20403023. The reversal of 20403021 is 12030402.

It is not a de Polignac number, because 20403021 - 2³ = 20403013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20402988 and 20403006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20403023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43836 + ... + 44298.

It is an arithmetic number, because the mean of its divisors is an integer number (1754384).

Almost surely, 2^20403021 is an apocalyptic number.

It is an amenable number.

20403021 is a deficient number, since it is larger than the sum of its proper divisors (7667123).

20403021 is a wasteful number, since it uses less digits than its factorization.

20403021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 900.

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 20403021 is about 4516.9703341953. The cubic root of 20403021 is about 273.2529287926.

Adding to 20403021 its reverse (12030402), we get a palindrome (32433423).

The spelling of 20403021 in words is "twenty million, four hundred three thousand, twenty-one".