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BaseRepresentation
bin100111000011101
31000102122
410320131
51114442
6232325
7112205
oct47035
930378
1019997
111402a
12b6a5
139143
147405
155dd2
hex4e1d

19997 has 2 divisors, whose sum is σ = 19998. Its totient is φ = 19996.

The previous prime is 19993. The next prime is 20011. The reversal of 19997 is 79991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19321 + 676 = 139^2 + 26^2 .

It is a cyclic number.

It is not a de Polignac number, because 19997 - 22 = 19993 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9998 + 9999.

It is an arithmetic number, because the mean of its divisors is an integer number (9999).

219997 is an apocalyptic number.

It is an amenable number.

19997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997 is an equidigital number, since it uses as much as digits as its factorization.

19997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5103, while the sum is 35.

The square root of 19997 is about 141.4107492378. The cubic root of 19997 is about 27.1428188893.

The spelling of 19997 in words is "nineteen thousand, nine hundred ninety-seven".