638965937280 has 512 divisors, whose sum is σ = 2280047616000. Its totient is φ = 150865182720.

The previous prime is 638965937221. The next prime is 638965937317. The reversal of 638965937280 is 82739569836.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 407763057 + ... + 407764623.

It is an arithmetic number, because the mean of its divisors is an integer number (4453218000).

Almost surely, 2^638965937280 is an apocalyptic number.

638965937280 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 638965937280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1140023808000).

638965937280 is an abundant number, since it is smaller than the sum of its proper divisors (1641081678720).

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

638965937280 is a wasteful number, since it uses less digits than its factorization.

638965937280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2092 (or 2080 counting only the distinct ones).

The product of its (nonzero) digits is 117573120, while the sum is 66.

The spelling of 638965937280 in words is "six hundred thirty-eight billion, nine hundred sixty-five million, nine hundred thirty-seven thousand, two hundred eighty".