51221240 has 32 divisors (see below), whose sum is σ = 131712480. Its totient is φ = 17561472.

The previous prime is 51221239. The next prime is 51221243. The reversal of 51221240 is 4212215.

51221240 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51221243) 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 7 ways as a sum of consecutive naturals, for example, 91187 + ... + 91746.

It is an arithmetic number, because the mean of its divisors is an integer number (4116015).

Almost surely, 2^51221240 is an apocalyptic number.

It is an amenable number.

51221240 is an abundant number, since it is smaller than the sum of its proper divisors (80491240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51221240 is a wasteful number, since it uses less digits than its factorization.

51221240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182951 (or 182947 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 51221240 is about 7156.9015642246. The cubic root of 51221240 is about 371.3784471667.

Adding to 51221240 its reverse (4212215), we get a palindrome (55433455).

The spelling of 51221240 in words is "fifty-one million, two hundred twenty-one thousand, two hundred forty".