221821404 has 48 divisors (see below), whose sum is σ = 592300800. Its totient is φ = 63294336.

The previous prime is 221821403. The next prime is 221821441. The reversal of 221821404 is 404128122.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221821403) 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, 93667 + ... + 96005.

It is an arithmetic number, because the mean of its divisors is an integer number (12339600).

Almost surely, 2^221821404 is an apocalyptic number.

It is an amenable number.

221821404 is an abundant number, since it is smaller than the sum of its proper divisors (370479396).

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

221821404 is a wasteful number, since it uses less digits than its factorization.

221821404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3482 (or 3480 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 221821404 is about 14893.6699305443. The cubic root of 221821404 is about 605.3424775875.

Adding to 221821404 its reverse (404128122), we get a palindrome (625949526).

The spelling of 221821404 in words is "two hundred twenty-one million, eight hundred twenty-one thousand, four hundred four".