215840 has 48 divisors (see below), whose sum is σ = 544320. Its totient is φ = 80640.

The previous prime is 215833. The next prime is 215843. The reversal of 215840 is 48512.

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

It is a nialpdrome in base 13.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 215840.

It is not an unprimeable number, because it can be changed into a prime (215843) by changing a digit.

215840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 3005 + ... + 3075.

It is an arithmetic number, because the mean of its divisors is an integer number (11340).

2²¹⁵⁸⁴⁰ is an apocalyptic number.

215840 is a gapful number since it is divisible by the number (20) 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 215840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (272160).

215840 is an abundant number, since it is smaller than the sum of its proper divisors (328480).

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

215840 is a wasteful number, since it uses less digits than its factorization.

215840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 215840 is about 464.5858370635. The cubic root of 215840 is about 59.9851815257.

It can be divided in two parts, 2158 and 40, that multiplied together give a triangular number (86320 = T₄₁₅).

The spelling of 215840 in words is "two hundred fifteen thousand, eight hundred forty".