208981609 has 2 divisors, whose sum is σ = 208981610. Its totient is φ = 208981608.

The previous prime is 208981607. The next prime is 208981621. The reversal of 208981609 is 906189802.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 196000000 + 12981609 = 14000^2 + 3603^2 .

It is a cyclic number.

It is not a de Polignac number, because 208981609 - 2¹ = 208981607 is a prime.

Together with 208981607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (208981603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104490804 + 104490805.

It is an arithmetic number, because the mean of its divisors is an integer number (104490805).

Almost surely, 2^208981609 is an apocalyptic number.

It is an amenable number.

208981609 is a deficient number, since it is larger than the sum of its proper divisors (1).

208981609 is an equidigital number, since it uses as much as digits as its factorization.

208981609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 208981609 is about 14456.1962147724. The cubic root of 208981609 is about 593.4298066909.

The spelling of 208981609 in words is "two hundred eight million, nine hundred eighty-one thousand, six hundred nine".