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21389357808 = 243271313911743
BaseRepresentation
bin10011111010111001…
…111011001011110000
32001012122211221212100
4103322321323023300
5322301133422213
613454240100400
71355022353520
oct237271731360
961178757770
1021389357808
11908680a115
12418b304700
13202b49b450
14106ca27680
15852c0c773
hex4fae7b2f0

21389357808 has 240 divisors, whose sum is σ = 74210805760. Its totient is φ = 5600088576.

The previous prime is 21389357797. The next prime is 21389357833. The reversal of 21389357808 is 80875398312.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1815585 + ... + 1827327.

Almost surely, 221389357808 is an apocalyptic number.

21389357808 is a gapful number since it is divisible by the number (28) 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 21389357808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37105402880).

21389357808 is an abundant number, since it is smaller than the sum of its proper divisors (52821447952).

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

21389357808 is a wasteful number, since it uses less digits than its factorization.

21389357808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11916 (or 11907 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 21389357808 in words is "twenty-one billion, three hundred eighty-nine million, three hundred fifty-seven thousand, eight hundred eight".