215540400 has 120 divisors (see below), whose sum is σ = 703682640. Its totient is φ = 56376320.

The previous prime is 215540371. The next prime is 215540401. The reversal of 215540400 is 4045512.

It is a tau number, because it is divible by the number of its divisors (120).

It is not an unprimeable number, because it can be changed into a prime (215540401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61906 + ... + 65294.

It is an arithmetic number, because the mean of its divisors is an integer number (5864022).

Almost surely, 2^215540400 is an apocalyptic number.

215540400 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 215540400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (351841320).

215540400 is an abundant number, since it is smaller than the sum of its proper divisors (488142240).

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

215540400 is a wasteful number, since it uses less digits than its factorization.

215540400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3463 (or 3452 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 215540400 is about 14681.2942208785. The cubic root of 215540400 is about 599.5741422579.

Adding to 215540400 its reverse (4045512), we get a palindrome (219585912).

The spelling of 215540400 in words is "two hundred fifteen million, five hundred forty thousand, four hundred".