661187 has 2 divisors, whose sum is σ = 661188. Its totient is φ = 661186.

The previous prime is 661183. The next prime is 661189. The reversal of 661187 is 781166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661187 - 2² = 661183 is a prime.

Together with 661189, it forms a pair of twin primes.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661187.

It is not a weakly prime, because it can be changed into another prime (661183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330593 + 330594.

It is an arithmetic number, because the mean of its divisors is an integer number (330594).

2⁶⁶¹¹⁸⁷ is an apocalyptic number.

661187 is a deficient number, since it is larger than the sum of its proper divisors (1).

661187 is an equidigital number, since it uses as much as digits as its factorization.

661187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 661187 is about 813.1340602877. The cubic root of 661187 is about 87.1180412055.

It can be divided in two parts, 661 and 187, that added together give a palindrome (848).

The spelling of 661187 in words is "six hundred sixty-one thousand, one hundred eighty-seven".