20630209 has 2 divisors, whose sum is σ = 20630210. Its totient is φ = 20630208.

The previous prime is 20630189. The next prime is 20630213. The reversal of 20630209 is 90203602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 199809 = 4520^2 + 447^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20630209 is a prime.

It is equal to p_1308019 and since 20630209 and 1308019 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20630209.

It is not a weakly prime, because it can be changed into another prime (20630249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10315104 + 10315105.

It is an arithmetic number, because the mean of its divisors is an integer number (10315105).

Almost surely, 2^20630209 is an apocalyptic number.

It is an amenable number.

20630209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20630209 is an equidigital number, since it uses as much as digits as its factorization.

20630209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 20630209 is about 4542.0489869661. The cubic root of 20630209 is about 274.2634128357.

The spelling of 20630209 in words is "twenty million, six hundred thirty thousand, two hundred nine".