221128400 has 30 divisors (see below), whose sum is σ = 531261942. Its totient is φ = 88451200.

The previous prime is 221128387. The next prime is 221128483. The reversal of 221128400 is 4821122.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 4096576 + 217031824 = 2024^2 + 14732^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 276011 + ... + 276810.

Almost surely, 2^221128400 is an apocalyptic number.

221128400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221128400 is an abundant number, since it is smaller than the sum of its proper divisors (310133542).

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

221128400 is a wasteful number, since it uses less digits than its factorization.

221128400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 552839 (or 552828 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 221128400 is about 14870.3866795723. The cubic root of 221128400 is about 604.7114257949.

Adding to 221128400 its reverse (4821122), we get a palindrome (225949522).

The spelling of 221128400 in words is "two hundred twenty-one million, one hundred twenty-eight thousand, four hundred".