1600661 has 4 divisors (see below), whose sum is σ = 1603212. Its totient is φ = 1598112.

The previous prime is 1600649. The next prime is 1600663. The reversal of 1600661 is 1660061.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 630436 + 970225 = 794^2 + 985^2 .

It is a cyclic number.

It is not a de Polignac number, because 1600661 - 2¹⁸ = 1338517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1600663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 401 + ... + 1833.

It is an arithmetic number, because the mean of its divisors is an integer number (400803).

2^1600661 is an apocalyptic number.

It is an amenable number.

1600661 is a deficient number, since it is larger than the sum of its proper divisors (2551).

1600661 is a wasteful number, since it uses less digits than its factorization.

1600661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2550.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 1600661 is about 1265.1723202789. The cubic root of 1600661 is about 116.9768137754.

The spelling of 1600661 in words is "one million, six hundred thousand, six hundred sixty-one".