51091 has 4 divisors (see below), whose sum is σ = 53800. Its totient is φ = 48384.
The previous prime is 51071. The next prime is 51109. The reversal of 51091 is 19015.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19015 = 5 ⋅3803.
It is a cyclic number.
It is not a de Polignac number, because 51091 - 25 = 51059 is a prime.
It is a super-2 number, since 2×510912 = 5220580562, which contains 22 as substring.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (51001) 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, 1326 + ... + 1363.
It is an arithmetic number, because the mean of its divisors is an integer number (13450).
251091 is an apocalyptic number.
51091 is the 131-st hex number.
51091 is a deficient number, since it is larger than the sum of its proper divisors (2709).
51091 is a wasteful number, since it uses less digits than its factorization.
51091 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 2708.
The product of its (nonzero) digits is 45, while the sum is 16.
The square root of 51091 is about 226.0331834046. The cubic root of 51091 is about 37.1063412608.
The spelling of 51091 in words is "fifty-one thousand, ninety-one".
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