639985464 has 96 divisors (see below), whose sum is σ = 1778400000. Its totient is φ = 207821376.

The previous prime is 639985457. The next prime is 639985471. The reversal of 639985464 is 464589936.

639985464 is a `hidden beast` number, since 6 + 3 + 9 + 98 + 546 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (639985457) and next prime (639985471).

It is a self number, because there is not a number n which added to its sum of digits gives 639985464.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1282287 + ... + 1282785.

It is an arithmetic number, because the mean of its divisors is an integer number (18525000).

Almost surely, 2^639985464 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 639985464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (889200000).

639985464 is an abundant number, since it is smaller than the sum of its proper divisors (1138414536).

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

639985464 is a wasteful number, since it uses less digits than its factorization.

639985464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 937 (or 930 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 54.

The square root of 639985464 is about 25297.9339867903. The cubic root of 639985464 is about 861.7673516170.

The spelling of 639985464 in words is "six hundred thirty-nine million, nine hundred eighty-five thousand, four hundred sixty-four".