660651 has 4 divisors (see below), whose sum is σ = 880872. Its totient is φ = 440432.

The previous prime is 660643. The next prime is 660659. The reversal of 660651 is 156066.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (660643) and next prime (660659).

It is a cyclic number.

It is not a de Polignac number, because 660651 - 2³ = 660643 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (660659) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110106 + ... + 110111.

It is an arithmetic number, because the mean of its divisors is an integer number (220218).

2⁶⁶⁰⁶⁵¹ is an apocalyptic number.

660651 is a deficient number, since it is larger than the sum of its proper divisors (220221).

660651 is a wasteful number, since it uses less digits than its factorization.

660651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220220.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 660651 is about 812.8044045156. The cubic root of 660651 is about 87.0944937099.

Adding to 660651 its sum of digits (24), we get a triangular number (660675 = T₁₁₄₉).

It can be divided in two parts, 66065 and 1, that added together give a palindrome (66066).

The spelling of 660651 in words is "six hundred sixty thousand, six hundred fifty-one".