87561 has 20 divisors (see below), whose sum is σ = 139392. Its totient is φ = 54648.

The previous prime is 87559. The next prime is 87583. The reversal of 87561 is 16578.

It is not a de Polignac number, because 87561 - 2¹ = 87559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1840 + ... + 1886.

2⁸⁷⁵⁶¹ is an apocalyptic number.

87561 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

87561 is a deficient number, since it is larger than the sum of its proper divisors (51831).

87561 is a wasteful number, since it uses less digits than its factorization.

87561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 73 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 87561 is about 295.9070800099. The cubic root of 87561 is about 44.4055142896.

It can be divided in two parts, 8 and 7561, that added together give a square (7569 = 87²).

The spelling of 87561 in words is "eighty-seven thousand, five hundred sixty-one".