987561 has 12 divisors (see below), whose sum is σ = 1436292. Its totient is φ = 653856.

The previous prime is 987559. The next prime is 987587. The reversal of 987561 is 165789.

987561 is a `hidden beast` number, since 98 + 7 + 561 = 666.

987561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 571536 + 416025 = 756^2 + 645^2 .

It is not a de Polignac number, because 987561 - 2¹ = 987559 is a prime.

It is a Curzon number.

987561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (987541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1495 + ... + 2051.

It is an arithmetic number, because the mean of its divisors is an integer number (119691).

2⁹⁸⁷⁵⁶¹ is an apocalyptic number.

It is an amenable number.

987561 is a deficient number, since it is larger than the sum of its proper divisors (448731).

987561 is a wasteful number, since it uses less digits than its factorization.

987561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 760 (or 757 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 987561 is about 993.7610376746. The cubic root of 987561 is about 99.5836354785.

The spelling of 987561 in words is "nine hundred eighty-seven thousand, five hundred sixty-one".