638401208 has 8 divisors (see below), whose sum is σ = 1197002280. Its totient is φ = 319200600.

The previous prime is 638401199. The next prime is 638401229. The reversal of 638401208 is 802104836.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×638401208² = 815112204751718528, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39900068 + ... + 39900083.

It is an arithmetic number, because the mean of its divisors is an integer number (149625285).

Almost surely, 2^638401208 is an apocalyptic number.

It is an amenable number.

638401208 is a deficient number, since it is larger than the sum of its proper divisors (558601072).

638401208 is a wasteful number, since it uses less digits than its factorization.

638401208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79800157 (or 79800153 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 638401208 is about 25266.6026208511. The cubic root of 638401208 is about 861.0556749340.

The spelling of 638401208 in words is "six hundred thirty-eight million, four hundred one thousand, two hundred eight".