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100999981 is a prime number
BaseRepresentation
bin1100000010100…
…10001100101101
321001001022221001
412001102030231
5201323444411
614004440301
72334325405
oct601221455
9231038831
10100999981
1152014865
12299a9091
1317c03a04
14d5b1805
158d00dc1
hex605232d

100999981 has 2 divisors, whose sum is σ = 100999982. Its totient is φ = 100999980.

The previous prime is 100999979. The next prime is 100999993. The reversal of 100999981 is 189999001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76842756 + 24157225 = 8766^2 + 4915^2 .

It is an emirp because it is prime and its reverse (189999001) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 100999981 - 21 = 100999979 is a prime.

It is a super-2 number, since 2×1009999812 = 20401992324000722, which contains 22 as substring.

Together with 100999979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (100999901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50499990 + 50499991.

It is an arithmetic number, because the mean of its divisors is an integer number (50499991).

Almost surely, 2100999981 is an apocalyptic number.

It is an amenable number.

100999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

100999981 is an equidigital number, since it uses as much as digits as its factorization.

100999981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 52488, while the sum is 46.

The square root of 100999981 is about 10049.8746758355. The cubic root of 100999981 is about 465.7009215780.

The spelling of 100999981 in words is "one hundred million, nine hundred ninety-nine thousand, nine hundred eighty-one".