215540240 has 20 divisors (see below), whose sum is σ = 501131244. Its totient is φ = 86216064.

The previous prime is 215540231. The next prime is 215540257. The reversal of 215540240 is 42045512.

It is a happy number.

215540240 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 49336576 + 166203664 = 7024^2 + 12892^2 .

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1347047 + ... + 1347206.

Almost surely, 2^215540240 is an apocalyptic number.

215540240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

215540240 is an abundant number, since it is smaller than the sum of its proper divisors (285591004).

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

215540240 is a wasteful number, since it uses less digits than its factorization.

215540240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2694266 (or 2694260 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 215540240 is about 14681.2887717666. The cubic root of 215540240 is about 599.5739938992.

Adding to 215540240 its reverse (42045512), we get a palindrome (257585752).

The spelling of 215540240 in words is "two hundred fifteen million, five hundred forty thousand, two hundred forty".