643523140 has 24 divisors (see below), whose sum is σ = 1455352920. Its totient is φ = 237608448.

The previous prime is 643523131. The next prime is 643523143. The reversal of 643523140 is 41325346.

It can be written as a sum of positive squares in 4 ways, for example, as 111851776 + 531671364 = 10576^2 + 23058^2 .

It is a junction number, because it is equal to n+sod(n) for n = 643523099 and 643523108.

It is not an unprimeable number, because it can be changed into a prime (643523143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1237285 + ... + 1237804.

It is an arithmetic number, because the mean of its divisors is an integer number (60639705).

Almost surely, 2^643523140 is an apocalyptic number.

It is an amenable number.

643523140 is an abundant number, since it is smaller than the sum of its proper divisors (811829780).

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

643523140 is a wasteful number, since it uses less digits than its factorization.

643523140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2475111 (or 2475109 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 28.

The square root of 643523140 is about 25367.7578827929. The cubic root of 643523140 is about 863.3523112988.

Adding to 643523140 its reverse (41325346), we get a palindrome (684848486).

The spelling of 643523140 in words is "six hundred forty-three million, five hundred twenty-three thousand, one hundred forty".