39840 has 48 divisors (see below), whose sum is σ = 127008. Its totient is φ = 10496.

The previous prime is 39839. The next prime is 39841. The reversal of 39840 is 4893.

It is an interprime number because it is at equal distance from previous prime (39839) and next prime (39841).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 39840.

It is not an unprimeable number, because it can be changed into a prime (39841) 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, 439 + ... + 521.

It is an arithmetic number, because the mean of its divisors is an integer number (2646).

2³⁹⁸⁴⁰ is an apocalyptic number.

39840 is a gapful number since it is divisible by the number (30) 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 39840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (63504).

39840 is an abundant number, since it is smaller than the sum of its proper divisors (87168).

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

39840 is a wasteful number, since it uses less digits than its factorization.

39840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101 (or 93 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 39840 is about 199.5995991980. The cubic root of 39840 is about 34.1538586403.

Adding to 39840 its product of nonzero digits (864), we get a palindrome (40704).

The spelling of 39840 in words is "thirty-nine thousand, eight hundred forty".