221020521 has 16 divisors (see below), whose sum is σ = 310520640. Its totient is φ = 139449600.

The previous prime is 221020517. The next prime is 221020523. The reversal of 221020521 is 125020122.

It is not a de Polignac number, because 221020521 - 2² = 221020517 is a prime.

It is a super-2 number, since 2×221020521² = 97700141406222882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221020521.

It is not an unprimeable number, because it can be changed into a prime (221020523) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101581 + ... + 103733.

It is an arithmetic number, because the mean of its divisors is an integer number (19407540).

Almost surely, 2^221020521 is an apocalyptic number.

It is an amenable number.

221020521 is a deficient number, since it is larger than the sum of its proper divisors (89500119).

221020521 is a wasteful number, since it uses less digits than its factorization.

221020521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3976.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 221020521 is about 14866.7589272175. The cubic root of 221020521 is about 604.6130722662.

Adding to 221020521 its reverse (125020122), we get a palindrome (346040643).

The spelling of 221020521 in words is "two hundred twenty-one million, twenty thousand, five hundred twenty-one".