651666 has 16 divisors (see below), whose sum is σ = 1311264. Its totient is φ = 215904.

The previous prime is 651649. The next prime is 651667. The reversal of 651666 is 666156.

651666 is nontrivially palindromic in base 5.

651666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 651666.

It is not an unprimeable number, because it can be changed into a prime (651667) by changing a digit.

651666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1705 + ... + 2051.

It is an arithmetic number, because the mean of its divisors is an integer number (81954).

2⁶⁵¹⁶⁶⁶ is an apocalyptic number.

651666 is an abundant number, since it is smaller than the sum of its proper divisors (659598).

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

651666 is a wasteful number, since it uses less digits than its factorization.

651666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665.

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

The square root of 651666 is about 807.2583229673. The cubic root of 651666 is about 86.6978553100.

The spelling of 651666 in words is "six hundred fifty-one thousand, six hundred sixty-six".