638995280 has 320 divisors, whose sum is σ = 1982016000. Its totient is φ = 189665280.

The previous prime is 638995271. The next prime is 638995283. The reversal of 638995280 is 82599836.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638995283) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8753324 + ... + 8753396.

It is an arithmetic number, because the mean of its divisors is an integer number (6193800).

Almost surely, 2^638995280 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 638995280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (991008000).

638995280 is an abundant number, since it is smaller than the sum of its proper divisors (1343020720).

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

638995280 is a wasteful number, since it uses less digits than its factorization.

638995280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 127 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 50.

The square root of 638995280 is about 25278.3559591996. The cubic root of 638995280 is about 861.3226807357.

The spelling of 638995280 in words is "six hundred thirty-eight million, nine hundred ninety-five thousand, two hundred eighty".