20013021 has 32 divisors (see below), whose sum is σ = 34592000. Its totient is φ = 11430720.

The previous prime is 20012999. The next prime is 20013031. The reversal of 20013021 is 12031002.

It is a happy number.

It is not a de Polignac number, because 20013021 - 2¹⁸ = 19750877 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20012994 and 20013012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20013031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8181 + ... + 10341.

It is an arithmetic number, because the mean of its divisors is an integer number (1081000).

Almost surely, 2^20013021 is an apocalyptic number.

20013021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20013021 is a deficient number, since it is larger than the sum of its proper divisors (14578979).

20013021 is an equidigital number, since it uses as much as digits as its factorization.

20013021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2191 (or 2171 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 20013021 is about 4473.5915101851. The cubic root of 20013021 is about 271.5006562665.

Adding to 20013021 its reverse (12031002), we get a palindrome (32044023).

The spelling of 20013021 in words is "twenty million, thirteen thousand, twenty-one".