993661 has 4 divisors (see below), whose sum is σ = 1001052. Its totient is φ = 986272.

The previous prime is 993647. The next prime is 993679. The reversal of 993661 is 166399.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 656100 + 337561 = 810^2 + 581^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-993661 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 (993611) 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 3 ways as a sum of consecutive naturals, for example, 3490 + ... + 3763.

It is an arithmetic number, because the mean of its divisors is an integer number (250263).

2⁹⁹³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

993661 is a deficient number, since it is larger than the sum of its proper divisors (7391).

993661 is a wasteful number, since it uses less digits than its factorization.

993661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7390.

The product of its digits is 8748, while the sum is 34.

The square root of 993661 is about 996.8254611515. The cubic root of 993661 is about 99.7882519441.

The spelling of 993661 in words is "nine hundred ninety-three thousand, six hundred sixty-one".