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19091981 is a prime number
BaseRepresentation
bin100100011010…
…1001000001101
31022220222021102
41020311020031
514341420411
61521112445
7321164516
oct110651015
938828242
1019091981
11a8600a7
126488725
133c5603c
14276da0d
151a21d3b
hex123520d

19091981 has 2 divisors, whose sum is σ = 19091982. Its totient is φ = 19091980.

The previous prime is 19091951. The next prime is 19091993. The reversal of 19091981 is 18919091.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12716356 + 6375625 = 3566^2 + 2525^2 .

It is an emirp because it is prime and its reverse (18919091) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 18616061 and 16061681.

It is a cyclic number.

It is not a de Polignac number, because 19091981 - 210 = 19090957 is a prime.

It is a super-2 number, since 2×190919812 = 729007477008722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19091911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9545990 + 9545991.

It is an arithmetic number, because the mean of its divisors is an integer number (9545991).

Almost surely, 219091981 is an apocalyptic number.

It is an amenable number.

19091981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19091981 is an equidigital number, since it uses as much as digits as its factorization.

19091981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 38.

The square root of 19091981 is about 4369.4371491074. The cubic root of 19091981 is about 267.2700723165.

The spelling of 19091981 in words is "nineteen million, ninety-one thousand, nine hundred eighty-one".