221381424 has 200 divisors, whose sum is σ = 714610512. Its totient is φ = 65594880.

The previous prime is 221381423. The next prime is 221381441. The reversal of 221381424 is 424183122.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (221381423) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 755422 + ... + 755714.

Almost surely, 2^221381424 is an apocalyptic number.

221381424 is a gapful number since it is divisible by the number (24) 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 221381424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (357305256).

221381424 is an abundant number, since it is smaller than the sum of its proper divisors (493229088).

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

221381424 is a wasteful number, since it uses less digits than its factorization.

221381424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377 (or 362 counting only the distinct ones).

The product of its digits is 3072, while the sum is 27.

The square root of 221381424 is about 14878.8918942238. The cubic root of 221381424 is about 604.9419829164.

The spelling of 221381424 in words is "two hundred twenty-one million, three hundred eighty-one thousand, four hundred twenty-four".