666651 has 8 divisors (see below), whose sum is σ = 892944. Its totient is φ = 442400.

The previous prime is 666649. The next prime is 666667. The reversal of 666651 is 156666.

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 666651 - 2¹ = 666649 is a prime.

It is a nialpdrome in base 10.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 666651.

It is not an unprimeable number, because it can be changed into a prime (666671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 601 + ... + 1301.

It is an arithmetic number, because the mean of its divisors is an integer number (111618).

2⁶⁶⁶⁶⁵¹ is an apocalyptic number.

666651 is a deficient number, since it is larger than the sum of its proper divisors (226293).

666651 is a wasteful number, since it uses less digits than its factorization.

666651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1021.

The product of its digits is 6480, while the sum is 30.

The square root of 666651 is about 816.4869870365. The cubic root of 666651 is about 87.3573621636.

It can be divided in two parts, 66665 and 1, that added together give a palindrome (66666).

The spelling of 666651 in words is "six hundred sixty-six thousand, six hundred fifty-one".