1661004 has 72 divisors (see below), whose sum is σ = 4564560. Its totient is φ = 508032.

The previous prime is 1661003. The next prime is 1661021. The reversal of 1661004 is 4001661.

1661004 is a `hidden beast` number, since 1 + 661 + 0 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (1661003) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38607 + ... + 38649.

2^1661004 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661004, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2282280).

1661004 is an abundant number, since it is smaller than the sum of its proper divisors (2903556).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661004 is a wasteful number, since it uses less digits than its factorization.

1661004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 1661004 is about 1288.7994413407. The cubic root of 1661004 is about 118.4286811148.

Adding to 1661004 its reverse (4001661), we get a palindrome (5662665).

The spelling of 1661004 in words is "one million, six hundred sixty-one thousand, four".