221520156 has 96 divisors (see below), whose sum is σ = 611670528. Its totient is φ = 61512960.

The previous prime is 221520151. The next prime is 221520163. The reversal of 221520156 is 651025122.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221520151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 286186 + ... + 286958.

It is an arithmetic number, because the mean of its divisors is an integer number (6371568).

Almost surely, 2^221520156 is an apocalyptic number.

221520156 is a gapful number since it is divisible by the number (26) 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 221520156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (305835264).

221520156 is an abundant number, since it is smaller than the sum of its proper divisors (390150372).

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

221520156 is a wasteful number, since it uses less digits than its factorization.

221520156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 971 (or 969 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 221520156 is about 14883.5532047962. The cubic root of 221520156 is about 605.0683218610.

Adding to 221520156 its reverse (651025122), we get a palindrome (872545278).

The spelling of 221520156 in words is "two hundred twenty-one million, five hundred twenty thousand, one hundred fifty-six".