209555989 has 2 divisors, whose sum is σ = 209555990. Its totient is φ = 209555988.

The previous prime is 209555977. The next prime is 209556041. The reversal of 209555989 is 989555902.

It is a happy number.

209555989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (209556041) can be obtained adding 209555989 to its sum of digits (52).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 113848900 + 95707089 = 10670^2 + 9783^2 .

It is a cyclic number.

It is not a de Polignac number, because 209555989 - 2⁹ = 209555477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209555909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104777994 + 104777995.

It is an arithmetic number, because the mean of its divisors is an integer number (104777995).

Almost surely, 2^209555989 is an apocalyptic number.

It is an amenable number.

209555989 is a deficient number, since it is larger than the sum of its proper divisors (1).

209555989 is an equidigital number, since it uses as much as digits as its factorization.

209555989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458000, while the sum is 52.

The square root of 209555989 is about 14476.0488048362. The cubic root of 209555989 is about 593.9729843321.

The spelling of 209555989 in words is "two hundred nine million, five hundred fifty-five thousand, nine hundred eighty-nine".