638601720 has 64 divisors (see below), whose sum is σ = 1930936320. Its totient is φ = 168948864.

The previous prime is 638601713. The next prime is 638601727. The reversal of 638601720 is 27106836.

It is an interprime number because it is at equal distance from previous prime (638601713) and next prime (638601727).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638601727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5712 + ... + 36191.

It is an arithmetic number, because the mean of its divisors is an integer number (30170880).

Almost surely, 2^638601720 is an apocalyptic number.

638601720 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 638601720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (965468160).

638601720 is an abundant number, since it is smaller than the sum of its proper divisors (1292334600).

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

638601720 is a wasteful number, since it uses less digits than its factorization.

638601720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42044 (or 42040 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 638601720 is about 25270.5702349591. The cubic root of 638601720 is about 861.1458136121.

The spelling of 638601720 in words is "six hundred thirty-eight million, six hundred one thousand, seven hundred twenty".