216681440 has 48 divisors (see below), whose sum is σ = 512794800. Its totient is φ = 86522880.

The previous prime is 216681419. The next prime is 216681457. The reversal of 216681440 is 44186612.

216681440 is digitally balanced in base 2, because in such base 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 (32).

It is a junction number, because it is equal to n+sod(n) for n = 216681397 and 216681406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 167195 + ... + 168485.

It is an arithmetic number, because the mean of its divisors is an integer number (10683225).

Almost surely, 2^216681440 is an apocalyptic number.

216681440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216681440 is an abundant number, since it is smaller than the sum of its proper divisors (296113360).

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

216681440 is a wasteful number, since it uses less digits than its factorization.

216681440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2355 (or 2347 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 216681440 is about 14720.1032605074. The cubic root of 216681440 is about 600.6303005997.

The spelling of 216681440 in words is "two hundred sixteen million, six hundred eighty-one thousand, four hundred forty".