639450784 has 192 divisors, whose sum is σ = 1632960000. Its totient is φ = 245059584.

The previous prime is 639450781. The next prime is 639450803. The reversal of 639450784 is 487054936.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is not an unprimeable number, because it can be changed into a prime (639450781) 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, 4291542 + ... + 4291690.

It is an arithmetic number, because the mean of its divisors is an integer number (8505000).

Almost surely, 2^639450784 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 639450784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (816480000).

639450784 is an abundant number, since it is smaller than the sum of its proper divisors (993509216).

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

639450784 is a wasteful number, since it uses less digits than its factorization.

639450784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 198 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 46.

The square root of 639450784 is about 25287.3641172820. The cubic root of 639450784 is about 861.5272950476.

The spelling of 639450784 in words is "six hundred thirty-nine million, four hundred fifty thousand, seven hundred eighty-four".