51445 has 4 divisors (see below), whose sum is σ = 61740. Its totient is φ = 41152.

The previous prime is 51439. The next prime is 51449. The reversal of 51445 is 54415.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54415 = 5 ⋅10883.

It can be written as a sum of positive squares in 2 ways, for example, as 33489 + 17956 = 183^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 51445 - 2³ = 51437 is a prime.

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51449) 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, 5140 + ... + 5149.

It is an arithmetic number, because the mean of its divisors is an integer number (15435).

2⁵¹⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

51445 is a deficient number, since it is larger than the sum of its proper divisors (10295).

51445 is a wasteful number, since it uses less digits than its factorization.

51445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10294.

The product of its digits is 400, while the sum is 19.

The square root of 51445 is about 226.8149025086. The cubic root of 51445 is about 37.1918450541.

It can be divided in two parts, 51 and 445, that added together give a triangular number (496 = T₃₁).

The spelling of 51445 in words is "fifty-one thousand, four hundred forty-five".