20061221 has 4 divisors (see below), whose sum is σ = 20933472. Its totient is φ = 19188972.

The previous prime is 20061199. The next prime is 20061269. The reversal of 20061221 is 12216002.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12216002 = 2 ⋅6108001.

It is a cyclic number.

It is not a de Polignac number, because 20061221 - 2¹⁰ = 20060197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20061196 and 20061205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20061271) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 436091 + ... + 436136.

It is an arithmetic number, because the mean of its divisors is an integer number (5233368).

Almost surely, 2^20061221 is an apocalyptic number.

It is an amenable number.

20061221 is a deficient number, since it is larger than the sum of its proper divisors (872251).

20061221 is an equidigital number, since it uses as much as digits as its factorization.

20061221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 872250.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 20061221 is about 4478.9754408793. The cubic root of 20061221 is about 271.7184451388.

Adding to 20061221 its reverse (12216002), we get a palindrome (32277223).

The spelling of 20061221 in words is "twenty million, sixty-one thousand, two hundred twenty-one".