638478959 has 4 divisors (see below), whose sum is σ = 640319304. Its totient is φ = 636638616.

The previous prime is 638478941. The next prime is 638478977. The reversal of 638478959 is 959874836.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (638478941) and next prime (638478977).

It is a cyclic number.

It is not a de Polignac number, because 638478959 - 2²⁸ = 370043503 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 638478898 and 638478907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638478989) 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, 919652 + ... + 920345.

It is an arithmetic number, because the mean of its divisors is an integer number (160079826).

Almost surely, 2^638478959 is an apocalyptic number.

638478959 is a deficient number, since it is larger than the sum of its proper divisors (1840345).

638478959 is a wasteful number, since it uses less digits than its factorization.

638478959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1840344.

The product of its digits is 13063680, while the sum is 59.

The square root of 638478959 is about 25268.1411860865. The cubic root of 638478959 is about 861.0906295578.

The spelling of 638478959 in words is "six hundred thirty-eight million, four hundred seventy-eight thousand, nine hundred fifty-nine".