1661006 has 4 divisors (see below), whose sum is σ = 2491512. Its totient is φ = 830502.

The previous prime is 1661003. The next prime is 1661021. The reversal of 1661006 is 6001661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6001661 = 251 ⋅23911.

It is a Curzon number.

It is a congruent number.

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 as a sum of consecutive naturals, namely, 415250 + ... + 415253.

It is an arithmetic number, because the mean of its divisors is an integer number (622878).

2^1661006 is an apocalyptic number.

1661006 is a deficient number, since it is larger than the sum of its proper divisors (830506).

1661006 is an equidigital number, since it uses as much as digits as its factorization.

1661006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830505.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 1661006 is about 1288.8002172563. The cubic root of 1661006 is about 118.4287286478.

Adding to 1661006 its reverse (6001661), we get a palindrome (7662667).

The spelling of 1661006 in words is "one million, six hundred sixty-one thousand, six".