987661 has 4 divisors (see below), whose sum is σ = 993024. Its totient is φ = 982300.

The previous prime is 987659. The next prime is 987697. The reversal of 987661 is 166789.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166789 = 7 ⋅23827.

It is a cyclic number.

It is not a de Polignac number, because 987661 - 2¹ = 987659 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 987661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (987631) 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, 2395 + ... + 2776.

It is an arithmetic number, because the mean of its divisors is an integer number (248256).

2⁹⁸⁷⁶⁶¹ is an apocalyptic number.

It is an amenable number.

987661 is a deficient number, since it is larger than the sum of its proper divisors (5363).

987661 is a wasteful number, since it uses less digits than its factorization.

987661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5362.

The product of its digits is 18144, while the sum is 37.

The square root of 987661 is about 993.8113503075. The cubic root of 987661 is about 99.5869966304.

The spelling of 987661 in words is "nine hundred eighty-seven thousand, six hundred sixty-one".