1661000 has 64 divisors (see below), whose sum is σ = 4268160. Its totient is φ = 600000.

The previous prime is 1660963. The next prime is 1661003. The reversal of 1661000 is 1661.

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 in 15 ways as a sum of consecutive naturals, for example, 10925 + ... + 11075.

It is an arithmetic number, because the mean of its divisors is an integer number (66690).

2^1661000 is an apocalyptic number.

1661000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2134080).

1661000 is an abundant number, since it is smaller than the sum of its proper divisors (2607160).

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

1661000 is a wasteful number, since it uses less digits than its factorization.

1661000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183 (or 169 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 1661000 is about 1288.7978895079. The cubic root of 1661000 is about 118.4285860488.

Adding to 1661000 its reverse (1661), we get a palindrome (1662661).

1661000 divided by its reverse (1661) gives a cube (1000 = 10³).

It can be divided in two parts, 16 and 61000, that added together give a palindrome (61016).

The spelling of 1661000 in words is "one million, six hundred sixty-one thousand".