1661885 has 8 divisors (see below), whose sum is σ = 2001240. Its totient is φ = 1324864.

The previous prime is 1661861. The next prime is 1661887. The reversal of 1661885 is 5881661.

It can be written as a sum of positive squares in 4 ways, for example, as 195364 + 1466521 = 442^2 + 1211^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661885 - 2⁸ = 1661629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661887) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2219 + ... + 2871.

It is an arithmetic number, because the mean of its divisors is an integer number (250155).

2^1661885 is an apocalyptic number.

It is an amenable number.

1661885 is a deficient number, since it is larger than the sum of its proper divisors (339355).

1661885 is an equidigital number, since it uses as much as digits as its factorization.

1661885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1167.

The product of its digits is 11520, while the sum is 35.

The square root of 1661885 is about 1289.1411869923. The cubic root of 1661885 is about 118.4496156875.

The spelling of 1661885 in words is "one million, six hundred sixty-one thousand, eight hundred eighty-five".