661775 has 12 divisors (see below), whose sum is σ = 831792. Its totient is φ = 522240.

The previous prime is 661769. The next prime is 661777. The reversal of 661775 is 577166.

It is a de Polignac number, because none of the positive numbers 2^k-661775 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661775.

It is not an unprimeable number, because it can be changed into a prime (661777) 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, 2447 + ... + 2703.

It is an arithmetic number, because the mean of its divisors is an integer number (69316).

2⁶⁶¹⁷⁷⁵ is an apocalyptic number.

661775 is a deficient number, since it is larger than the sum of its proper divisors (170017).

661775 is a wasteful number, since it uses less digits than its factorization.

661775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370 (or 365 counting only the distinct ones).

The product of its digits is 8820, while the sum is 32.

The square root of 661775 is about 813.4955439337. The cubic root of 661775 is about 87.1438585263.

The spelling of 661775 in words is "six hundred sixty-one thousand, seven hundred seventy-five".