20130021 has 12 divisors (see below), whose sum is σ = 29167372. Its totient is φ = 13378176.

The previous prime is 20130001. The next prime is 20130029. The reversal of 20130021 is 12003102.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2160900 + 17969121 = 1470^2 + 4239^2 .

It is not a de Polignac number, because 20130021 - 2⁶ = 20129957 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 = 20129985 and 20130012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20130029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 286 + ... + 6351.

Almost surely, 2^20130021 is an apocalyptic number.

It is an amenable number.

20130021 is a deficient number, since it is larger than the sum of its proper divisors (9037351).

20130021 is a wasteful number, since it uses less digits than its factorization.

20130021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6980 (or 6977 counting only the distinct ones).

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

The square root of 20130021 is about 4486.6491951121. The cubic root of 20130021 is about 272.0287103849.

Adding to 20130021 its reverse (12003102), we get a palindrome (32133123).

The spelling of 20130021 in words is "twenty million, one hundred thirty thousand, twenty-one".