1661818 has 16 divisors (see below), whose sum is σ = 2712744. Its totient is φ = 760320.

The previous prime is 1661813. The next prime is 1661827. The reversal of 1661818 is 8181661.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1570009 + 91809 = 1253^2 + 303^2 .

1661818 is a modest number, since divided by 1818 gives 166 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 1661818.

It is not an unprimeable number, because it can be changed into a prime (1661813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 598 + ... + 1918.

2^1661818 is an apocalyptic number.

1661818 is a deficient number, since it is larger than the sum of its proper divisors (1050926).

1661818 is a wasteful number, since it uses less digits than its factorization.

1661818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1377.

The product of its digits is 2304, while the sum is 31.

The square root of 1661818 is about 1289.1152004379. The cubic root of 1661818 is about 118.4480238744.

The spelling of 1661818 in words is "one million, six hundred sixty-one thousand, eight hundred eighteen".