661791 has 16 divisors (see below), whose sum is σ = 967680. Its totient is φ = 399840.

The previous prime is 661777. The next prime is 661823. The reversal of 661791 is 197166.

661791 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 661791 - 2⁷ = 661663 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661721) 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, 2650 + ... + 2888.

It is an arithmetic number, because the mean of its divisors is an integer number (60480).

2⁶⁶¹⁷⁹¹ is an apocalyptic number.

661791 is a deficient number, since it is larger than the sum of its proper divisors (305889).

661791 is a wasteful number, since it uses less digits than its factorization.

661791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326.

The product of its digits is 2268, while the sum is 30.

The square root of 661791 is about 813.5053779785. The cubic root of 661791 is about 87.1445608246.

The spelling of 661791 in words is "six hundred sixty-one thousand, seven hundred ninety-one".