221520621312 has 144 divisors (see below), whose sum is σ = 655318091680. Its totient is φ = 73812860928.

The previous prime is 221520621293. The next prime is 221520621319. The reversal of 221520621312 is 213126025122.

221520621312 is a `hidden beast` number, since 2 + 2 + 1 + 5 + 2 + 0 + 621 + 31 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221520621319) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 28701678 + ... + 28709394.

Almost surely, 2^221520621312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221520621312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (327659045840).

221520621312 is an abundant number, since it is smaller than the sum of its proper divisors (433797470368).

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

221520621312 is an equidigital number, since it uses as much as digits as its factorization.

221520621312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11895 (or 11875 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

Adding to 221520621312 its reverse (213126025122), we get a palindrome (434646646434).

The spelling of 221520621312 in words is "two hundred twenty-one billion, five hundred twenty million, six hundred twenty-one thousand, three hundred twelve".