51500 has 24 divisors (see below), whose sum is σ = 113568. Its totient is φ = 20400.

The previous prime is 51487. The next prime is 51503. The reversal of 51500 is 515.

It is a hoax number, since the sum of its digits (11) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (51503) 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, 449 + ... + 551.

It is an arithmetic number, because the mean of its divisors is an integer number (4732).

2⁵¹⁵⁰⁰ is an apocalyptic number.

51500 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56784).

51500 is an abundant number, since it is smaller than the sum of its proper divisors (62068).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51500 is a wasteful number, since it uses less digits than its factorization.

51500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 25, while the sum is 11.

The square root of 51500 is about 226.9361143582. The cubic root of 51500 is about 37.2050943037.

Multiplying 51500 by its reverse (515), we get a square (26522500 = 5150²).

51500 divided by its reverse (515) gives a square (100 = 10²).

The spelling of 51500 in words is "fifty-one thousand, five hundred".