661745 has 24 divisors (see below), whose sum is σ = 961704. Its totient is φ = 435456.

The previous prime is 661741. The next prime is 661769. The reversal of 661745 is 547166.

It can be written as a sum of positive squares in 4 ways, for example, as 200704 + 461041 = 448^2 + 679^2 .

It is not a de Polignac number, because 661745 - 2² = 661741 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9029 + ... + 9101.

It is an arithmetic number, because the mean of its divisors is an integer number (40071).

2⁶⁶¹⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

661745 is a deficient number, since it is larger than the sum of its proper divisors (299959).

661745 is a wasteful number, since it uses less digits than its factorization.

661745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 122 counting only the distinct ones).

The product of its digits is 5040, while the sum is 29.

The square root of 661745 is about 813.4771047792. The cubic root of 661745 is about 87.1425416863.

The spelling of 661745 in words is "six hundred sixty-one thousand, seven hundred forty-five".