661859 has 4 divisors (see below), whose sum is σ = 722040. Its totient is φ = 601680.

The previous prime is 661849. The next prime is 661873. The reversal of 661859 is 958166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661859 - 2⁸ = 661603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30074 + ... + 30095.

It is an arithmetic number, because the mean of its divisors is an integer number (180510).

2⁶⁶¹⁸⁵⁹ is an apocalyptic number.

661859 is a deficient number, since it is larger than the sum of its proper divisors (60181).

661859 is a wasteful number, since it uses less digits than its factorization.

661859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60180.

The product of its digits is 12960, while the sum is 35.

The square root of 661859 is about 813.5471713429. The cubic root of 661859 is about 87.1475454664.

The spelling of 661859 in words is "six hundred sixty-one thousand, eight hundred fifty-nine".