221520331 has 4 divisors (see below), whose sum is σ = 221785200. Its totient is φ = 221255464.

The previous prime is 221520317. The next prime is 221520347. The reversal of 221520331 is 133025122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 133025122 = 2 ⋅66512561.

It is a cyclic number.

It is not a de Polignac number, because 221520331 - 2¹³ = 221512139 is a prime.

It is a super-2 number, since 2×221520331² = 98142514092699122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221520299 and 221520308.

It is not an unprimeable number, because it can be changed into a prime (221520361) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 131176 + ... + 132853.

It is an arithmetic number, because the mean of its divisors is an integer number (55446300).

Almost surely, 2^221520331 is an apocalyptic number.

221520331 is a deficient number, since it is larger than the sum of its proper divisors (264869).

221520331 is an equidigital number, since it uses as much as digits as its factorization.

221520331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264868.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 221520331 is about 14883.5590837676. The cubic root of 221520331 is about 605.0684811947.

Adding to 221520331 its reverse (133025122), we get a palindrome (354545453).

The spelling of 221520331 in words is "two hundred twenty-one million, five hundred twenty thousand, three hundred thirty-one".