20110221 has 8 divisors (see below), whose sum is σ = 29792960. Its totient is φ = 13406796.

The previous prime is 20110217. The next prime is 20110229. The reversal of 20110221 is 12201102.

It is not a de Polignac number, because 20110221 - 2² = 20110217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20110229) 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, 372385 + ... + 372438.

It is an arithmetic number, because the mean of its divisors is an integer number (3724120).

Almost surely, 2^20110221 is an apocalyptic number.

It is an amenable number.

20110221 is a deficient number, since it is larger than the sum of its proper divisors (9682739).

20110221 is an equidigital number, since it uses as much as digits as its factorization.

20110221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 744832 (or 744826 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 20110221 is about 4484.4421057697. The cubic root of 20110221 is about 271.9394914784.

Adding to 20110221 its reverse (12201102), we get a palindrome (32311323).

The spelling of 20110221 in words is "twenty million, one hundred ten thousand, two hundred twenty-one".