1663209 has 12 divisors (see below), whose sum is σ = 2418052. Its totient is φ = 1101600.

The previous prime is 1663183. The next prime is 1663217. The reversal of 1663209 is 9023661.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 363609 + 1299600 = 603^2 + 1140^2 .

It is not a de Polignac number, because 1663209 - 2⁸ = 1662953 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1663219) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1119 + ... + 2139.

2^1663209 is an apocalyptic number.

It is an amenable number.

1663209 is a deficient number, since it is larger than the sum of its proper divisors (754843).

1663209 is a wasteful number, since it uses less digits than its factorization.

1663209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208 (or 1205 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 1663209 is about 1289.6546049233. The cubic root of 1663209 is about 118.4810630424.

It can be divided in two parts, 166 and 3209, that added together give a cube (3375 = 15³).

The spelling of 1663209 in words is "one million, six hundred sixty-three thousand, two hundred nine".