20750221 has 4 divisors (see below), whose sum is σ = 20940700. Its totient is φ = 20559744.

The previous prime is 20750203. The next prime is 20750227. The reversal of 20750221 is 12205702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12205702 = 2 ⋅6102851.

It can be written as a sum of positive squares in 2 ways, for example, as 4862025 + 15888196 = 2205^2 + 3986^2 .

It is a cyclic number.

It is not a de Polignac number, because 20750221 - 2¹⁵ = 20717453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20750227) 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, 95076 + ... + 95293.

It is an arithmetic number, because the mean of its divisors is an integer number (5235175).

Almost surely, 2^20750221 is an apocalyptic number.

It is an amenable number.

20750221 is a deficient number, since it is larger than the sum of its proper divisors (190479).

20750221 is a wasteful number, since it uses less digits than its factorization.

20750221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190478.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 20750221 is about 4555.2410474090. The cubic root of 20750221 is about 274.7942085724.

Adding to 20750221 its reverse (12205702), we get a palindrome (32955923).

The spelling of 20750221 in words is "twenty million, seven hundred fifty thousand, two hundred twenty-one".