1661655 has 8 divisors (see below), whose sum is σ = 2658672. Its totient is φ = 886208.

The previous prime is 1661641. The next prime is 1661659. The reversal of 1661655 is 5561661.

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 1661655 - 2⁵ = 1661623 is a prime.

It is a super-2 number, since 2×1661655² = 5522194678050, which contains 22 as substring.

1661655 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661659) 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, 55374 + ... + 55403.

It is an arithmetic number, because the mean of its divisors is an integer number (332334).

2^1661655 is an apocalyptic number.

1661655 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1661655 is a deficient number, since it is larger than the sum of its proper divisors (997017).

1661655 is a wasteful number, since it uses less digits than its factorization.

1661655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110785.

The product of its digits is 5400, while the sum is 30.

The square root of 1661655 is about 1289.0519772298. The cubic root of 1661655 is about 118.4441510758. Note that the first 3 decimals are identical.

The spelling of 1661655 in words is "one million, six hundred sixty-one thousand, six hundred fifty-five".