651665 has 16 divisors (see below), whose sum is σ = 916608. Its totient is φ = 435456.

The previous prime is 651649. The next prime is 651667. The reversal of 651665 is 566156.

651665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 651665 - 2⁴ = 651649 is a prime.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

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

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1289 + ... + 1721.

It is an arithmetic number, because the mean of its divisors is an integer number (57288).

2⁶⁵¹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

651665 is a deficient number, since it is larger than the sum of its proper divisors (264943).

651665 is a wasteful number, since it uses less digits than its factorization.

651665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488.

The product of its digits is 5400, while the sum is 29.

The square root of 651665 is about 807.2577035867. The cubic root of 651665 is about 86.6978109632.

It can be divided in two parts, 651 and 665, that multiplied together give a triangular number (432915 = T₉₃₀).

The spelling of 651665 in words is "six hundred fifty-one thousand, six hundred sixty-five".