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20720 = 245737
BaseRepresentation
bin101000011110000
31001102102
411003300
51130340
6235532
7114260
oct50360
931372
1020720
1114627
12bba8
13957b
1477a0
156215
hex50f0

20720 has 40 divisors (see below), whose sum is σ = 56544. Its totient is φ = 6912.

The previous prime is 20719. The next prime is 20731. The reversal of 20720 is 2702.

It can be divided in two parts, 20 and 720, that multiplied together give a square (14400 = 1202).

20720 is nontrivially palindromic in base 6.

It is a tau number, because it is divible by the number of its divisors (40).

It is a nialpdrome in base 12.

It is a zygodrome in base 4.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 542 + ... + 578.

220720 is an apocalyptic number.

20720 is a gapful number since it is divisible by the number (20) 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 20720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28272).

20720 is an abundant number, since it is smaller than the sum of its proper divisors (35824).

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

20720 is a wasteful number, since it uses less digits than its factorization.

20720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57 (or 51 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 11.

The square root of 20720 is about 143.9444337236. The cubic root of 20720 is about 27.4660738658.

The spelling of 20720 in words is "twenty thousand, seven hundred twenty", and thus it is an iban number.