638404416 has 140 divisors (see below), whose sum is σ = 2038217412. Its totient is φ = 196411392.

The previous prime is 638404409. The next prime is 638404423. The reversal of 638404416 is 614404836.

638404416 is a `hidden beast` number, since 638 + 4 + 0 + 4 + 4 + 16 = 666.

It is an interprime number because it is at equal distance from previous prime (638404409) and next prime (638404423).

It can be written as a sum of positive squares in 2 ways, for example, as 392040000 + 246364416 = 19800^2 + 15696^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 62656 + ... + 72128.

Almost surely, 2^638404416 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638404416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1019108706).

638404416 is an abundant number, since it is smaller than the sum of its proper divisors (1399812996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638404416 is a wasteful number, since it uses less digits than its factorization.

638404416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9510 (or 9491 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 638404416 is about 25266.6661037819. Note that the first 3 decimals coincide. The cubic root of 638404416 is about 861.0571172151.

The spelling of 638404416 in words is "six hundred thirty-eight million, four hundred four thousand, four hundred sixteen".