643545 has 40 divisors (see below), whose sum is σ = 1324224. Its totient is φ = 292896.

The previous prime is 643523. The next prime is 643547. The reversal of 643545 is 545346.

643545 = T₁₇₄ + T₁₇₅ + ... + T₂₀₈.

643545 is nontrivially palindromic in base 16.

643545 is a nontrivial binomial coefficient, being equal to C(1135, 2).

It is not a de Polignac number, because 643545 - 2¹³ = 635353 is a prime.

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

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2722 + ... + 2948.

2⁶⁴³⁵⁴⁵ is an apocalyptic number.

643545 is the 1134-th triangular number.

It is an amenable number.

643545 is an abundant number, since it is smaller than the sum of its proper divisors (680679).

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

643545 is a wasteful number, since it uses less digits than its factorization.

643545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251 (or 242 counting only the distinct ones).

The product of its digits is 7200, while the sum is 27.

The square root of 643545 is about 802.2125653466. The cubic root of 643545 is about 86.3362086999.

The spelling of 643545 in words is "six hundred forty-three thousand, five hundred forty-five".