287661 has 16 divisors (see below), whose sum is σ = 437760. Its totient is φ = 166320.

The previous prime is 287629. The next prime is 287669. The reversal of 287661 is 166782.

It is a happy number.

287661 is a nontrivial binomial coefficient, being equal to C(759, 2).

It is not a de Polignac number, because 287661 - 2⁵ = 287629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (287669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 570 + ... + 948.

It is an arithmetic number, because the mean of its divisors is an integer number (27360).

2²⁸⁷⁶⁶¹ is an apocalyptic number.

287661 is the 758-th triangular number.

It is an amenable number.

287661 is a deficient number, since it is larger than the sum of its proper divisors (150099).

287661 is a wasteful number, since it uses less digits than its factorization.

287661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 416.

The product of its digits is 4032, while the sum is 30.

The square root of 287661 is about 536.3403769995. The cubic root of 287661 is about 66.0126238479.

The spelling of 287661 in words is "two hundred eighty-seven thousand, six hundred sixty-one".