1663555 has 4 divisors (see below), whose sum is σ = 1996272. Its totient is φ = 1330840.

The previous prime is 1663549. The next prime is 1663579. The reversal of 1663555 is 5553661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5553661 = 47 ⋅118163.

It is not a de Polignac number, because 1663555 - 2³ = 1663547 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166351 + ... + 166360.

It is an arithmetic number, because the mean of its divisors is an integer number (499068).

2^1663555 is an apocalyptic number.

1663555 is a deficient number, since it is larger than the sum of its proper divisors (332717).

1663555 is an equidigital number, since it uses as much as digits as its factorization.

1663555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332716.

The product of its digits is 13500, while the sum is 31.

The square root of 1663555 is about 1289.7887423916. The cubic root of 1663555 is about 118.4892784071.

It can be divided in two parts, 166 and 3555, that added together give a square (3721 = 61²).

The spelling of 1663555 in words is "one million, six hundred sixty-three thousand, five hundred fifty-five".