638556667 has 16 divisors (see below), whose sum is σ = 747921600. Its totient is φ = 533849472.

The previous prime is 638556661. The next prime is 638556671. The reversal of 638556667 is 766655836.

It is a cyclic number.

It is not a de Polignac number, because 638556667 - 2²³ = 630168059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638556661) 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, 59209 + ... + 69157.

It is an arithmetic number, because the mean of its divisors is an integer number (46745100).

Almost surely, 2^638556667 is an apocalyptic number.

638556667 is a deficient number, since it is larger than the sum of its proper divisors (109364933).

638556667 is a wasteful number, since it uses less digits than its factorization.

638556667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10182.

The product of its digits is 5443200, while the sum is 52.

The square root of 638556667 is about 25269.6788068230. The cubic root of 638556667 is about 861.1255620147.

The spelling of 638556667 in words is "six hundred thirty-eight million, five hundred fifty-six thousand, six hundred sixty-seven".