216405240 has 128 divisors (see below), whose sum is σ = 703676160. Its totient is φ = 53028864.

The previous prime is 216405209. The next prime is 216405251. The reversal of 216405240 is 42504612.

216405240 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

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 216405240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86487 + ... + 88953.

It is an arithmetic number, because the mean of its divisors is an integer number (5497470).

Almost surely, 2^216405240 is an apocalyptic number.

216405240 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 216405240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (351838080).

216405240 is an abundant number, since it is smaller than the sum of its proper divisors (487270920).

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

216405240 is a wasteful number, since it uses less digits than its factorization.

216405240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2541 (or 2537 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 216405240 is about 14710.7185412542. The cubic root of 216405240 is about 600.3749878136.

Adding to 216405240 its reverse (42504612), we get a palindrome (258909852).

The spelling of 216405240 in words is "two hundred sixteen million, four hundred five thousand, two hundred forty".