661867 has 6 divisors (see below), whose sum is σ = 686348. Its totient is φ = 638232.

The previous prime is 661849. The next prime is 661873. The reversal of 661867 is 768166.

661867 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661867 - 2¹¹ = 659819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661877) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 448 + ... + 1234.

2⁶⁶¹⁸⁶⁷ is an apocalyptic number.

661867 is a deficient number, since it is larger than the sum of its proper divisors (24481).

661867 is an equidigital number, since it uses as much as digits as its factorization.

661867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845 (or 816 counting only the distinct ones).

The product of its digits is 12096, while the sum is 34.

The square root of 661867 is about 813.5520880681. The cubic root of 661867 is about 87.1478965873.

The spelling of 661867 in words is "six hundred sixty-one thousand, eight hundred sixty-seven".