638658020 has 384 divisors, whose sum is σ = 2005032960. Its totient is φ = 164229120.

The previous prime is 638657959. The next prime is 638658029. The reversal of 638658020 is 20856836.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is not an unprimeable number, because it can be changed into a prime (638658029) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 8748704 + ... + 8748776.

It is an arithmetic number, because the mean of its divisors is an integer number (5221440).

Almost surely, 2^638658020 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 638658020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1002516480).

638658020 is an abundant number, since it is smaller than the sum of its proper divisors (1366374940).

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

638658020 is a wasteful number, since it uses less digits than its factorization.

638658020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 153 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 638658020 is about 25271.6841544049. The cubic root of 638658020 is about 861.1711194655.

The spelling of 638658020 in words is "six hundred thirty-eight million, six hundred fifty-eight thousand, twenty".