51491 has 8 divisors (see below), whose sum is σ = 58368. Its totient is φ = 45000.

The previous prime is 51487. The next prime is 51503. The reversal of 51491 is 19415.

51491 = T₁₂₈ + T₁₂₉ + ... + T₁₃₃.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51491 - 2² = 51487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 266 + ... + 416.

It is an arithmetic number, because the mean of its divisors is an integer number (7296).

2⁵¹⁴⁹¹ is an apocalyptic number.

51491 is a deficient number, since it is larger than the sum of its proper divisors (6877).

51491 is a wasteful number, since it uses less digits than its factorization.

51491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193.

The product of its digits is 180, while the sum is 20.

The square root of 51491 is about 226.9162841226. The cubic root of 51491 is about 37.2029268904.

The spelling of 51491 in words is "fifty-one thousand, four hundred ninety-one".