71840 has 24 divisors (see below), whose sum is σ = 170100. Its totient is φ = 28672.

The previous prime is 71837. The next prime is 71843. The reversal of 71840 is 4817.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (71837) and next prime (71843).

It can be written as a sum of positive squares in 2 ways, for example, as 71824 + 16 = 268^2 + 4^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65 + ... + 384.

2⁷¹⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

71840 is an abundant number, since it is smaller than the sum of its proper divisors (98260).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85050).

71840 is a wasteful number, since it uses less digits than its factorization.

71840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464 (or 456 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 71840 is about 268.0298490840. The cubic root of 71840 is about 41.5708375495.

It can be divided in two parts, 7 and 1840, that multiplied together give a triangular number (12880 = T₁₆₀).

The spelling of 71840 in words is "seventy-one thousand, eight hundred forty".