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81639168 = 2831321737
BaseRepresentation
bin1001101110110…
…11011100000000
312200121200212220
410313123130000
5131344423133
612033451040
72010631032
oct467333400
9180550786
1081639168
11420a0796
1223410a80
1313bb5500
14abb1c52
1572795b3
hex4ddb700

81639168 has 216 divisors, whose sum is σ = 255851568. Its totient is φ = 23003136.

The previous prime is 81639163. The next prime is 81639179. The reversal of 81639168 is 86193618.

Its product of digits (62208) is a multiple of the sum of its prime divisors (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81639163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2206446 + ... + 2206482.

It is an arithmetic number, because the mean of its divisors is an integer number (1184498).

Almost surely, 281639168 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 81639168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127925784).

81639168 is an abundant number, since it is smaller than the sum of its proper divisors (174212400).

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

81639168 is a wasteful number, since it uses less digits than its factorization.

81639168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 72 counting only the distinct ones).

The product of its digits is 62208, while the sum is 42.

The square root of 81639168 is about 9035.4395576530. The cubic root of 81639168 is about 433.8099644416.

The spelling of 81639168 in words is "eighty-one million, six hundred thirty-nine thousand, one hundred sixty-eight".