51870 has 64 divisors (see below), whose sum is σ = 161280. Its totient is φ = 10368.

The previous prime is 51869. The next prime is 51871. The reversal of 51870 is 7815.

Added to its reverse (7815) it gives a triangular number (59685 = T₃₄₅).

51870 = T₃₆ + T₃₇ + ... + T₇₀.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (51869) and next prime (51871).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 51870.

It is not an unprimeable number, because it can be changed into a prime (51871) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2721 + ... + 2739.

It is an arithmetic number, because the mean of its divisors is an integer number (2520).

2⁵¹⁸⁷⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80640).

51870 is an abundant number, since it is smaller than the sum of its proper divisors (109410).

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

51870 is a wasteful number, since it uses less digits than its factorization.

51870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 51870 is about 227.7498627881. The cubic root of 51870 is about 37.2939813523.

Adding to 51870 its reverse (7815), we get a triangular number (59685 = T₃₄₅).

The spelling of 51870 in words is "fifty-one thousand, eight hundred seventy".