638547840 has 256 divisors, whose sum is σ = 2585088000. Its totient is φ = 145926144.

The previous prime is 638547803. The next prime is 638547853. The reversal of 638547840 is 48745836.

638547840 is a `hidden beast` number, since 63 + 8 + 547 + 8 + 40 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118321 + ... + 123599.

It is an arithmetic number, because the mean of its divisors is an integer number (10098000).

Almost surely, 2^638547840 is an apocalyptic number.

638547840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638547840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1292544000).

638547840 is an abundant number, since it is smaller than the sum of its proper divisors (1946540160).

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

638547840 is a wasteful number, since it uses less digits than its factorization.

638547840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5314 (or 5296 counting only the distinct ones).

The product of its (nonzero) digits is 645120, while the sum is 45.

The square root of 638547840 is about 25269.5041502599. The cubic root of 638547840 is about 861.1215941129.

The spelling of 638547840 in words is "six hundred thirty-eight million, five hundred forty-seven thousand, eight hundred forty".