221235521 has 8 divisors (see below), whose sum is σ = 238578984. Its totient is φ = 203938560.

The previous prime is 221235517. The next prime is 221235527. The reversal of 221235521 is 125532122.

221235521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 297025 + 220938496 = 545^2 + 14864^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221235521 - 2² = 221235517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221235527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1400 + ... + 21081.

It is an arithmetic number, because the mean of its divisors is an integer number (29822373).

Almost surely, 2^221235521 is an apocalyptic number.

It is an amenable number.

221235521 is a deficient number, since it is larger than the sum of its proper divisors (17343463).

221235521 is a wasteful number, since it uses less digits than its factorization.

221235521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23251.

The product of its digits is 1200, while the sum is 23.

The square root of 221235521 is about 14873.9880664198. The cubic root of 221235521 is about 604.8090566065.

Adding to 221235521 its reverse (125532122), we get a palindrome (346767643).

The spelling of 221235521 in words is "two hundred twenty-one million, two hundred thirty-five thousand, five hundred twenty-one".