643525138 has 8 divisors (see below), whose sum is σ = 998573580. Its totient is φ = 310667280.

The previous prime is 643525121. The next prime is 643525139. The reversal of 643525138 is 831525346.

It can be written as a sum of positive squares in 2 ways, for example, as 642470409 + 1054729 = 25347^2 + 1027^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 643525097 and 643525106.

It is not an unprimeable number, because it can be changed into a prime (643525139) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5547573 + ... + 5547688.

Almost surely, 2^643525138 is an apocalyptic number.

643525138 is a deficient number, since it is larger than the sum of its proper divisors (355048442).

643525138 is a wasteful number, since it uses less digits than its factorization.

643525138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11095292.

The product of its digits is 86400, while the sum is 37.

The square root of 643525138 is about 25367.7972634598. The cubic root of 643525138 is about 863.3532048052.

The spelling of 643525138 in words is "six hundred forty-three million, five hundred twenty-five thousand, one hundred thirty-eight".