638820279 has 6 divisors (see below), whose sum is σ = 922740416. Its totient is φ = 425880180.

The previous prime is 638820263. The next prime is 638820311. The reversal of 638820279 is 972028836.

638820279 is a `hidden beast` number, since 638 + 8 + 2 + 0 + 2 + 7 + 9 = 666.

It is not a de Polignac number, because 638820279 - 2⁴ = 638820263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638820229) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35490007 + ... + 35490024.

Almost surely, 2^638820279 is an apocalyptic number.

638820279 is a deficient number, since it is larger than the sum of its proper divisors (283920137).

638820279 is a wasteful number, since it uses less digits than its factorization.

638820279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70980037 (or 70980034 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 638820279 is about 25274.8942431022. The cubic root of 638820279 is about 861.2440436954.

The spelling of 638820279 in words is "six hundred thirty-eight million, eight hundred twenty thousand, two hundred seventy-nine".