638213312751840 has 720 divisors, whose sum is σ = 2716738083192672. Its totient is φ = 138199567398912.

The previous prime is 638213312751809. The next prime is 638213312751851. The reversal of 638213312751840 is 48157213312836.

638213312751840 is a `hidden beast` number, since 6 + 3 + 8 + 21 + 331 + 275 + 18 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 23006182 + ... + 42493658.

Almost surely, 2^{638213312751840} is an apocalyptic number.

638213312751840 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 638213312751840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1358369041596336).

638213312751840 is an abundant number, since it is smaller than the sum of its proper divisors (2078524770440832).

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

638213312751840 is a wasteful number, since it uses less digits than its factorization.

638213312751840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19487549 (or 19487513 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 54.

The spelling of 638213312751840 in words is "six hundred thirty-eight trillion, two hundred thirteen billion, three hundred twelve million, seven hundred fifty-one thousand, eight hundred forty".