215440 has 20 divisors (see below), whose sum is σ = 501084. Its totient is φ = 86144.

The previous prime is 215417. The next prime is 215443. The reversal of 215440 is 44512.

It can be written as a sum of positive squares in 2 ways, for example, as 82944 + 132496 = 288^2 + 364^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (215443) 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 3 ways as a sum of consecutive naturals, for example, 1267 + ... + 1426.

2²¹⁵⁴⁴⁰ is an apocalyptic number.

215440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

215440 is an abundant number, since it is smaller than the sum of its proper divisors (285644).

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

215440 is a wasteful number, since it uses less digits than its factorization.

215440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2706 (or 2700 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 215440 is about 464.1551464758. The cubic root of 215440 is about 59.9481032733.

Adding to 215440 its reverse (44512), we get a palindrome (259952).

The spelling of 215440 in words is "two hundred fifteen thousand, four hundred forty".