639742608 has 120 divisors (see below), whose sum is σ = 1876754880. Its totient is φ = 203047680.

The previous prime is 639742583. The next prime is 639742619. The reversal of 639742608 is 806247936.

639742608 is a `hidden beast` number, since 6 + 39 + 7 + 4 + 2 + 608 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1387498 + ... + 1387958.

It is an arithmetic number, because the mean of its divisors is an integer number (15639624).

Almost surely, 2^639742608 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 639742608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (938377440).

639742608 is an abundant number, since it is smaller than the sum of its proper divisors (1237012272).

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

639742608 is a wasteful number, since it uses less digits than its factorization.

639742608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 917 (or 908 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The square root of 639742608 is about 25293.1336136905. The cubic root of 639742608 is about 861.6583325523.

The spelling of 639742608 in words is "six hundred thirty-nine million, seven hundred forty-two thousand, six hundred eight".