1661663 has 2 divisors, whose sum is σ = 1661664. Its totient is φ = 1661662.

The previous prime is 1661659. The next prime is 1661669. The reversal of 1661663 is 3661661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1661663 - 2² = 1661659 is a prime.

It is a super-2 number, since 2×1661663² = 5522247851138, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830831 + 830832.

It is an arithmetic number, because the mean of its divisors is an integer number (830832).

2^1661663 is an apocalyptic number.

1661663 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661663 is an equidigital number, since it uses as much as digits as its factorization.

1661663 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 29.

The square root of 1661663 is about 1289.0550802817. The cubic root of 1661663 is about 118.4443411577. Note that the first 3 decimals are identical.

The spelling of 1661663 in words is "one million, six hundred sixty-one thousand, six hundred sixty-three".