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638947680 = 25357397479
BaseRepresentation
bin100110000101011…
…001000101100000
31122112021220102220
4212011121011200
52302032311210
6143222511040
721555652140
oct4605310540
91575256386
10638947680
112a873a938
12159b95480
13a24b4467
1460c04920
153b162c70
hex26159160

638947680 has 192 divisors, whose sum is σ = 2310819840. Its totient is φ = 145373184.

The previous prime is 638947679. The next prime is 638947681. The reversal of 638947680 is 86749836.

It is an interprime number because it is at equal distance from previous prime (638947679) and next prime (638947681).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638947681) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1333681 + ... + 1334159.

It is an arithmetic number, because the mean of its divisors is an integer number (12035520).

Almost surely, 2638947680 is an apocalyptic number.

638947680 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 638947680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1155409920).

638947680 is an abundant number, since it is smaller than the sum of its proper divisors (1671872160).

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

638947680 is a wasteful number, since it uses less digits than its factorization.

638947680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 901 (or 893 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 51.

The square root of 638947680 is about 25277.4144247389. The cubic root of 638947680 is about 861.3012930046.

The spelling of 638947680 in words is "six hundred thirty-eight million, nine hundred forty-seven thousand, six hundred eighty".