51221424 has 80 divisors (see below), whose sum is σ = 141419520. Its totient is φ = 15939840.

The previous prime is 51221419. The next prime is 51221441. The reversal of 51221424 is 42412215.

It is a self number, because there is not a number n which added to its sum of digits gives 51221424.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42559 + ... + 43745.

It is an arithmetic number, because the mean of its divisors is an integer number (1767744).

Almost surely, 2^51221424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51221424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (70709760).

51221424 is an abundant number, since it is smaller than the sum of its proper divisors (90198096).

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

51221424 is a wasteful number, since it uses less digits than its factorization.

51221424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258 (or 1252 counting only the distinct ones).

The product of its digits is 640, while the sum is 21.

The square root of 51221424 is about 7156.9144189378. The cubic root of 51221424 is about 371.3788918621.

Adding to 51221424 its reverse (42412215), we get a palindrome (93633639).

The spelling of 51221424 in words is "fifty-one million, two hundred twenty-one thousand, four hundred twenty-four".