221312320 has 56 divisors (see below), whose sum is σ = 530050248. Its totient is φ = 88012800.

The previous prime is 221312303. The next prime is 221312353. The reversal of 221312320 is 23213122.

It can be written as a sum of positive squares in 4 ways, for example, as 9784384 + 211527936 = 3128^2 + 14544^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 221312294 and 221312303.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56010 + ... + 59830.

It is an arithmetic number, because the mean of its divisors is an integer number (9465183).

Almost surely, 2^221312320 is an apocalyptic number.

221312320 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 221312320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (265025124).

221312320 is an abundant number, since it is smaller than the sum of its proper divisors (308737928).

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

221312320 is a wasteful number, since it uses less digits than its factorization.

221312320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4019 (or 4009 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 221312320 is about 14876.5694970312. The cubic root of 221312320 is about 604.8790323453.

Adding to 221312320 its reverse (23213122), we get a palindrome (244525442).

The spelling of 221312320 in words is "two hundred twenty-one million, three hundred twelve thousand, three hundred twenty".