638440187 has 16 divisors (see below), whose sum is σ = 830587392. Its totient is φ = 475854720.

The previous prime is 638440183. The next prime is 638440199. The reversal of 638440187 is 781044836.

It is not a de Polignac number, because 638440187 - 2² = 638440183 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638440183) 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 15 ways as a sum of consecutive naturals, for example, 178478 + ... + 182019.

It is an arithmetic number, because the mean of its divisors is an integer number (51911712).

Almost surely, 2^638440187 is an apocalyptic number.

638440187 is a deficient number, since it is larger than the sum of its proper divisors (192147205).

638440187 is a wasteful number, since it uses less digits than its factorization.

638440187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360538.

The product of its (nonzero) digits is 129024, while the sum is 41.

The square root of 638440187 is about 25267.3739632752. The cubic root of 638440187 is about 861.0731991313.

The spelling of 638440187 in words is "six hundred thirty-eight million, four hundred forty thousand, one hundred eighty-seven".