661758 has 16 divisors (see below), whose sum is σ = 1349136. Its totient is φ = 216320.

The previous prime is 661741. The next prime is 661769. The reversal of 661758 is 857166.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 723 + ... + 1358.

It is an arithmetic number, because the mean of its divisors is an integer number (84321).

2⁶⁶¹⁷⁵⁸ is an apocalyptic number.

661758 is an abundant number, since it is smaller than the sum of its proper divisors (687378).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661758 is a wasteful number, since it uses less digits than its factorization.

661758 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2139.

The product of its digits is 10080, while the sum is 33.

The square root of 661758 is about 813.4850951308. The cubic root of 661758 is about 87.1431123218.

The spelling of 661758 in words is "six hundred sixty-one thousand, seven hundred fifty-eight".