638189550 has 96 divisors (see below), whose sum is σ = 1775109600. Its totient is φ = 168583680.

The previous prime is 638189543. The next prime is 638189567. The reversal of 638189550 is 55981836.

638189550 is a `hidden beast` number, since 638 + 1 + 8 + 9 + 5 + 5 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 638189496 and 638189505.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 144982 + ... + 149318.

It is an arithmetic number, because the mean of its divisors is an integer number (18490725).

Almost surely, 2^638189550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638189550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (887554800).

638189550 is an abundant number, since it is smaller than the sum of its proper divisors (1136920050).

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

638189550 is a wasteful number, since it uses less digits than its factorization.

638189550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4467 (or 4456 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The square root of 638189550 is about 25262.4137801596. The cubic root of 638189550 is about 860.9605051752.

The spelling of 638189550 in words is "six hundred thirty-eight million, one hundred eighty-nine thousand, five hundred fifty".