51440221 has 4 divisors (see below), whose sum is σ = 58788832. Its totient is φ = 44091612.

The previous prime is 51440203. The next prime is 51440237. The reversal of 51440221 is 12204415.

51440221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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: 12204415 = 5 ⋅2440883.

It is a cyclic number.

It is not a de Polignac number, because 51440221 - 2⁵ = 51440189 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 (51440251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3674295 + ... + 3674308.

It is an arithmetic number, because the mean of its divisors is an integer number (14697208).

Almost surely, 2^51440221 is an apocalyptic number.

It is an amenable number.

51440221 is a deficient number, since it is larger than the sum of its proper divisors (7348611).

51440221 is an equidigital number, since it uses as much as digits as its factorization.

51440221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7348610.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 51440221 is about 7172.1838375769. The cubic root of 51440221 is about 371.9069336888.

Adding to 51440221 its reverse (12204415), we get a palindrome (63644636).

The spelling of 51440221 in words is "fifty-one million, four hundred forty thousand, two hundred twenty-one".