221620320 has 288 divisors, whose sum is σ = 816510240. Its totient is φ = 56125440.

The previous prime is 221620297. The next prime is 221620337. The reversal of 221620320 is 23026122.

221620320 is a `hidden beast` number, since 2 + 21 + 620 + 3 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 221620293 and 221620302.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3633090 + ... + 3633150.

It is an arithmetic number, because the mean of its divisors is an integer number (2835105).

Almost surely, 2^221620320 is an apocalyptic number.

221620320 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 221620320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (408255120).

221620320 is an abundant number, since it is smaller than the sum of its proper divisors (594889920).

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

221620320 is a wasteful number, since it uses less digits than its factorization.

221620320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 221620320 is about 14886.9177468004. The cubic root of 221620320 is about 605.1595053332.

Adding to 221620320 its reverse (23026122), we get a palindrome (244646442).

The spelling of 221620320 in words is "two hundred twenty-one million, six hundred twenty thousand, three hundred twenty".