221212400 has 60 divisors (see below), whose sum is σ = 534185304. Its totient is φ = 88032000.

The previous prime is 221212361. The next prime is 221212423. The reversal of 221212400 is 4212122.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 83090 + ... + 85710.

Almost surely, 2^221212400 is an apocalyptic number.

221212400 is a gapful number since it is divisible by the number (20) 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 221212400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (267092652).

221212400 is an abundant number, since it is smaller than the sum of its proper divisors (312972904).

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

221212400 is a wasteful number, since it uses less digits than its factorization.

221212400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2850 (or 2839 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 221212400 is about 14873.2108167672. The cubic root of 221212400 is about 604.7879866365.

Adding to 221212400 its reverse (4212122), we get a palindrome (225424522).

The spelling of 221212400 in words is "two hundred twenty-one million, two hundred twelve thousand, four hundred".