20630021 has 2 divisors, whose sum is σ = 20630022. Its totient is φ = 20630020.

The previous prime is 20630003. The next prime is 20630023. The reversal of 20630021 is 12003602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 280900 = 4511^2 + 530^2 .

It is a cyclic number.

It is not a de Polignac number, because 20630021 - 2²² = 16435717 is a prime.

Together with 20630023, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20629978 and 20630005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20630023) 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 as a sum of consecutive naturals, namely, 10315010 + 10315011.

It is an arithmetic number, because the mean of its divisors is an integer number (10315011).

Almost surely, 2^20630021 is an apocalyptic number.

It is an amenable number.

20630021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20630021 is an equidigital number, since it uses as much as digits as its factorization.

20630021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 20630021 is about 4542.0282914134. The cubic root of 20630021 is about 274.2625797261.

Adding to 20630021 its reverse (12003602), we get a palindrome (32633623).

The spelling of 20630021 in words is "twenty million, six hundred thirty thousand, twenty-one".