221816420 has 24 divisors (see below), whose sum is σ = 532359744. Its totient is φ = 76051296.

The previous prime is 221816411. The next prime is 221816423. The reversal of 221816420 is 24618122.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 221816420.

It is not an unprimeable number, because it can be changed into a prime (221816423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 792062 + ... + 792341.

It is an arithmetic number, because the mean of its divisors is an integer number (22181656).

Almost surely, 2^221816420 is an apocalyptic number.

221816420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221816420 is an abundant number, since it is smaller than the sum of its proper divisors (310543324).

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

221816420 is a wasteful number, since it uses less digits than its factorization.

221816420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1584419 (or 1584417 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 221816420 is about 14893.5026101989. The cubic root of 221816420 is about 605.3379438358.

The spelling of 221816420 in words is "two hundred twenty-one million, eight hundred sixteen thousand, four hundred twenty".