638217923 has 16 divisors (see below), whose sum is σ = 768606720. Its totient is φ = 517694976.

The previous prime is 638217917. The next prime is 638217941. The reversal of 638217923 is 329712836.

It is not a de Polignac number, because 638217923 - 2⁸ = 638217667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638217913) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 159890 + ... + 163832.

It is an arithmetic number, because the mean of its divisors is an integer number (48037920).

Almost surely, 2^638217923 is an apocalyptic number.

638217923 is a deficient number, since it is larger than the sum of its proper divisors (130388797).

638217923 is a wasteful number, since it uses less digits than its factorization.

638217923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5186.

The product of its digits is 108864, while the sum is 41.

The square root of 638217923 is about 25262.9753394172. The cubic root of 638217923 is about 860.9732640128.

The spelling of 638217923 in words is "six hundred thirty-eight million, two hundred seventeen thousand, nine hundred twenty-three".