25511221 has 4 divisors (see below), whose sum is σ = 25553452. Its totient is φ = 25468992.

The previous prime is 25511207. The next prime is 25511231. The reversal of 25511221 is 12211552.

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 13359025 + 12152196 = 3655^2 + 3486^2 .

It is a 3-Lehmer number, since φ(25511221) divides (25511221-1)³.

It is a cyclic number.

It is not a de Polignac number, because 25511221 - 2¹¹ = 25509173 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 (25511201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20196 + ... + 21421.

It is an arithmetic number, because the mean of its divisors is an integer number (6388363).

Almost surely, 2^25511221 is an apocalyptic number.

It is an amenable number.

25511221 is a deficient number, since it is larger than the sum of its proper divisors (42231).

25511221 is an equidigital number, since it uses as much as digits as its factorization.

25511221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42230.

The product of its digits is 200, while the sum is 19.

The square root of 25511221 is about 5050.8633915401. The cubic root of 25511221 is about 294.3814329729.

Adding to 25511221 its reverse (12211552), we get a palindrome (37722773).

It can be divided in two parts, 255 and 11221, that added together give a triangular number (11476 = T₁₅₁).

The spelling of 25511221 in words is "twenty-five million, five hundred eleven thousand, two hundred twenty-one".