661751 has 8 divisors (see below), whose sum is σ = 721200. Its totient is φ = 604800.

The previous prime is 661741. The next prime is 661769. The reversal of 661751 is 157166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661751 - 2¹⁰ = 660727 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661751.

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 661751.

It is not an unprimeable number, because it can be changed into a prime (661721) by changing a digit.

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, 50 + ... + 1151.

It is an arithmetic number, because the mean of its divisors is an integer number (90150).

2⁶⁶¹⁷⁵¹ is an apocalyptic number.

661751 is a deficient number, since it is larger than the sum of its proper divisors (59449).

661751 is a wasteful number, since it uses less digits than its factorization.

661751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1249.

The product of its digits is 1260, while the sum is 26.

The square root of 661751 is about 813.4807926436. The cubic root of 661751 is about 87.1428050575.

The spelling of 661751 in words is "six hundred sixty-one thousand, seven hundred fifty-one".