20310021 has 10 divisors (see below), whose sum is σ = 30339782. Its totient is φ = 13539960.

The previous prime is 20310007. The next prime is 20310023. The reversal of 20310021 is 12001302.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17969121 + 2340900 = 4239^2 + 1530^2 .

It is not a de Polignac number, because 20310021 - 2⁷ = 20309893 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 = 20309985 and 20310012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20310023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 125290 + ... + 125451.

Almost surely, 2^20310021 is an apocalyptic number.

It is an amenable number.

20310021 is a deficient number, since it is larger than the sum of its proper divisors (10029761).

20310021 is an equidigital number, since it uses as much as digits as its factorization.

20310021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250753 (or 250744 counting only the distinct ones).

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

The square root of 20310021 is about 4506.6640655811. The cubic root of 20310021 is about 272.8371205682.

Adding to 20310021 its reverse (12001302), we get a palindrome (32311323).

The spelling of 20310021 in words is "twenty million, three hundred ten thousand, twenty-one".