216431440 has 80 divisors (see below), whose sum is σ = 516038400. Its totient is φ = 84395520.

The previous prime is 216431419. The next prime is 216431443. The reversal of 216431440 is 44134612.

216431440 = T₁₉ + T₂₀ + ... + T₁₀₉₀.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216431443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 798505 + ... + 798775.

It is an arithmetic number, because the mean of its divisors is an integer number (6450480).

Almost surely, 2^216431440 is an apocalyptic number.

216431440 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 216431440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (258019200).

216431440 is an abundant number, since it is smaller than the sum of its proper divisors (299606960).

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

216431440 is a wasteful number, since it uses less digits than its factorization.

216431440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500 (or 494 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 216431440 is about 14711.6090214497. The cubic root of 216431440 is about 600.3992158005.

The spelling of 216431440 in words is "two hundred sixteen million, four hundred thirty-one thousand, four hundred forty".