1661659 has 2 divisors, whose sum is σ = 1661660. Its totient is φ = 1661658.

The previous prime is 1661641. The next prime is 1661663. The reversal of 1661659 is 9561661.

It is a strong prime.

It is an emirp because it is prime and its reverse (9561661) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661659 is a prime.

It is a super-2 number, since 2×1661659² = 5522221264562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1661629) 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 as a sum of consecutive naturals, namely, 830829 + 830830.

It is an arithmetic number, because the mean of its divisors is an integer number (830830).

2^1661659 is an apocalyptic number.

1661659 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661659 is an equidigital number, since it uses as much as digits as its factorization.

1661659 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9720, while the sum is 34.

The square root of 1661659 is about 1289.0535287567. The cubic root of 1661659 is about 118.4442461169. Note that the first 3 decimals are identical.

The spelling of 1661659 in words is "one million, six hundred sixty-one thousand, six hundred fifty-nine".