216507438 has 128 divisors (see below), whose sum is σ = 571069440. Its totient is φ = 59529600.

The previous prime is 216507407. The next prime is 216507439. The reversal of 216507438 is 834705612.

216507438 is a `hidden beast` number, since 216 + 5 + 0 + 7 + 438 = 666.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216507439) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2023381 + ... + 2023487.

It is an arithmetic number, because the mean of its divisors is an integer number (4461480).

Almost surely, 2^216507438 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216507438, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (285534720).

216507438 is an abundant number, since it is smaller than the sum of its proper divisors (354562002).

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

216507438 is a wasteful number, since it uses less digits than its factorization.

216507438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 216507438 is about 14714.1917209203. The cubic root of 216507438 is about 600.4694825477.

The spelling of 216507438 in words is "two hundred sixteen million, five hundred seven thousand, four hundred thirty-eight".