51005 has 6 divisors (see below), whose sum is σ = 61818. Its totient is φ = 40400.

The previous prime is 51001. The next prime is 51031. The reversal of 51005 is 50015.

It can be written as a sum of positive squares in 3 ways, for example, as 31684 + 19321 = 178^2 + 139^2 .

It is not a de Polignac number, because 51005 - 2² = 51001 is a prime.

It is a Duffinian number.

It is a congruent 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 5 ways as a sum of consecutive naturals, for example, 455 + ... + 555.

It is an arithmetic number, because the mean of its divisors is an integer number (10303).

2⁵¹⁰⁰⁵ is an apocalyptic number.

It is an amenable number.

51005 is a deficient number, since it is larger than the sum of its proper divisors (10813).

51005 is an equidigital number, since it uses as much as digits as its factorization.

51005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207 (or 106 counting only the distinct ones).

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

The square root of 51005 is about 225.8428657275. The cubic root of 51005 is about 37.0855095582.

Subtracting from 51005 its reverse (50015), we obtain a triangular number (990 = T₄₄).

The spelling of 51005 in words is "fifty-one thousand, five".