51223440 has 80 divisors (see below), whose sum is σ = 161828928. Its totient is φ = 13398528.

The previous prime is 51223433. The next prime is 51223451. The reversal of 51223440 is 4432215.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 10707 + ... + 14733.

Almost surely, 2^51223440 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 51223440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80914464).

51223440 is an abundant number, since it is smaller than the sum of its proper divisors (110605488).

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

51223440 is a wasteful number, since it uses less digits than its factorization.

51223440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4096 (or 4090 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 51223440 is about 7157.0552603707. The cubic root of 51223440 is about 371.3837641074.

Adding to 51223440 its reverse (4432215), we get a palindrome (55655655).

The spelling of 51223440 in words is "fifty-one million, two hundred twenty-three thousand, four hundred forty".