661887 has 12 divisors (see below), whose sum is σ = 963144. Its totient is φ = 438000.

The previous prime is 661883. The next prime is 661889. The reversal of 661887 is 788166.

It is not a de Polignac number, because 661887 - 2² = 661883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661883) 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, 2113 + ... + 2405.

It is an arithmetic number, because the mean of its divisors is an integer number (80262).

2⁶⁶¹⁸⁸⁷ is an apocalyptic number.

661887 is a deficient number, since it is larger than the sum of its proper divisors (301257).

661887 is a wasteful number, since it uses less digits than its factorization.

661887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550 (or 547 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 661887 is about 813.5643797512. The cubic root of 661887 is about 87.1487743771.

It can be divided in two parts, 66 and 1887, that added together give a triangular number (1953 = T₆₂).

The spelling of 661887 in words is "six hundred sixty-one thousand, eight hundred eighty-seven".