20021161 has 4 divisors (see below), whose sum is σ = 20509524. Its totient is φ = 19532800.

The previous prime is 20021159. The next prime is 20021171. The reversal of 20021161 is 16112002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7595536 + 12425625 = 2756^2 + 3525^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021161 - 2¹ = 20021159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20021171) 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, 244120 + ... + 244201.

It is an arithmetic number, because the mean of its divisors is an integer number (5127381).

Almost surely, 2^20021161 is an apocalyptic number.

It is an amenable number.

20021161 is a deficient number, since it is larger than the sum of its proper divisors (488363).

20021161 is an equidigital number, since it uses as much as digits as its factorization.

20021161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488362.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 20021161 is about 4474.5012012514. The cubic root of 20021161 is about 271.5374609012.

Adding to 20021161 its reverse (16112002), we get a palindrome (36133163).

The spelling of 20021161 in words is "twenty million, twenty-one thousand, one hundred sixty-one".