25205421 has 4 divisors (see below), whose sum is σ = 33607232. Its totient is φ = 16803612.

The previous prime is 25205417. The next prime is 25205429. The reversal of 25205421 is 12450252.

It is a happy number.

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.

It is not a de Polignac number, because 25205421 - 2² = 25205417 is a prime.

It is the 5021-st Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25205429) by changing a digit.

It is a nontrivial repunit in base 5020.

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, 4200901 + ... + 4200906.

It is an arithmetic number, because the mean of its divisors is an integer number (8401808).

Almost surely, 2^25205421 is an apocalyptic number.

It is an amenable number.

25205421 is a deficient number, since it is larger than the sum of its proper divisors (8401811).

25205421 is an equidigital number, since it uses as much as digits as its factorization.

25205421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8401810.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 25205421 is about 5020.5000746938. The cubic root of 25205421 is about 293.2004630958.

Adding to 25205421 its reverse (12450252), we get a palindrome (37655673).

The spelling of 25205421 in words is "twenty-five million, two hundred five thousand, four hundred twenty-one".