638776320 has 352 divisors, whose sum is σ = 2520069888. Its totient is φ = 134479872.

The previous prime is 638776291. The next prime is 638776321. The reversal of 638776320 is 23677836.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638776321) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1397532 + ... + 1397988.

Almost surely, 2^638776320 is an apocalyptic number.

638776320 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 638776320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1260034944).

638776320 is an abundant number, since it is smaller than the sum of its proper divisors (1881293568).

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

638776320 is a wasteful number, since it uses less digits than its factorization.

638776320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505 (or 487 counting only the distinct ones).

The product of its (nonzero) digits is 254016, while the sum is 42.

The square root of 638776320 is about 25274.0246102594. The cubic root of 638776320 is about 861.2242883763.

The spelling of 638776320 in words is "six hundred thirty-eight million, seven hundred seventy-six thousand, three hundred twenty".