643653 has 16 divisors (see below), whose sum is σ = 985600. Its totient is φ = 414720.

The previous prime is 643651. The next prime is 643661. The reversal of 643653 is 356346.

643653 is a `hidden beast` number, since 6 + 4 + 3 + 653 = 666.

It is not a de Polignac number, because 643653 - 2¹ = 643651 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a d-powerful number, because it can be written as 6 + 4⁸ + 6⁶ + 3² + 5 + 3¹² .

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643651) 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, 453 + ... + 1221.

It is an arithmetic number, because the mean of its divisors is an integer number (61600).

2⁶⁴³⁶⁵³ is an apocalyptic number.

It is an amenable number.

643653 is a deficient number, since it is larger than the sum of its proper divisors (341947).

643653 is a wasteful number, since it uses less digits than its factorization.

643653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 809 (or 803 counting only the distinct ones).

The product of its digits is 6480, while the sum is 27.

The square root of 643653 is about 802.2798763524. The cubic root of 643653 is about 86.3410380897.

Adding to 643653 its reverse (356346), we get a palindrome (999999).

It can be divided in two parts, 643 and 653, that added together give a 4-th power (1296 = 6⁴).

The spelling of 643653 in words is "six hundred forty-three thousand, six hundred fifty-three".