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20729 = 191091
BaseRepresentation
bin101000011111001
31001102202
411003321
51130404
6235545
7114302
oct50371
931382
1020729
1114635
12bbb5
139587
1477a9
15621e
hex50f9

20729 has 4 divisors (see below), whose sum is σ = 21840. Its totient is φ = 19620.

The previous prime is 20719. The next prime is 20731. The reversal of 20729 is 92702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 92702 = 246351.

It is a cyclic number.

It is not a de Polignac number, because 20729 - 212 = 16633 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a self number, because there is not a number n which added to its sum of digits gives 20729.

It is not an unprimeable number, because it can be changed into a prime (20719) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527 + ... + 564.

It is an arithmetic number, because the mean of its divisors is an integer number (5460).

220729 is an apocalyptic number.

It is an amenable number.

20729 is a deficient number, since it is larger than the sum of its proper divisors (1111).

20729 is a wasteful number, since it uses less digits than its factorization.

20729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 20729 is about 143.9756923928. The cubic root of 20729 is about 27.4700500383.

The spelling of 20729 in words is "twenty thousand, seven hundred twenty-nine".

Divisors: 1 19 1091 20729