221312400 has 120 divisors (see below), whose sum is σ = 725593440. Its totient is φ = 57630720.

The previous prime is 221312393. The next prime is 221312411. The reversal of 221312400 is 4213122.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 221312400.

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 23 ways as a sum of consecutive naturals, for example, 49456 + ... + 53744.

It is an arithmetic number, because the mean of its divisors is an integer number (6046612).

Almost surely, 2^221312400 is an apocalyptic number.

221312400 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 221312400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (362796720).

221312400 is an abundant number, since it is smaller than the sum of its proper divisors (504281040).

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

221312400 is a wasteful number, since it uses less digits than its factorization.

221312400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4353 (or 4342 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 221312400 is about 14876.5721858229. The cubic root of 221312400 is about 604.8791052292.

Adding to 221312400 its reverse (4213122), we get a palindrome (225525522).

It can be divided in two parts, 22131 and 2400, that added together give a triangular number (24531 = T₂₂₁).

The spelling of 221312400 in words is "two hundred twenty-one million, three hundred twelve thousand, four hundred".