643521372 has 24 divisors (see below), whose sum is σ = 1617054096. Its totient is φ = 198006528.

The previous prime is 643521371. The next prime is 643521407. The reversal of 643521372 is 273125346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643521371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2062413 + ... + 2062724.

It is an arithmetic number, because the mean of its divisors is an integer number (67377254).

Almost surely, 2^643521372 is an apocalyptic number.

It is an amenable number.

643521372 is an abundant number, since it is smaller than the sum of its proper divisors (973532724).

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

643521372 is a wasteful number, since it uses less digits than its factorization.

643521372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4125157 (or 4125155 counting only the distinct ones).

The product of its digits is 30240, while the sum is 33.

The square root of 643521372 is about 25367.7230353849. The cubic root of 643521372 is about 863.3515206470.

The spelling of 643521372 in words is "six hundred forty-three million, five hundred twenty-one thousand, three hundred seventy-two".