51489440 has 96 divisors (see below), whose sum is σ = 128024064. Its totient is φ = 19548160.

The previous prime is 51489421. The next prime is 51489457. The reversal of 51489440 is 4498415.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 51489440.

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, 308237 + ... + 308403.

It is an arithmetic number, because the mean of its divisors is an integer number (1333584).

Almost surely, 2^51489440 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 51489440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (64012032).

51489440 is an abundant number, since it is smaller than the sum of its proper divisors (76534624).

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

51489440 is a wasteful number, since it uses less digits than its factorization.

51489440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270 (or 262 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 51489440 is about 7175.6142594206. The cubic root of 51489440 is about 372.0255117972.

Subtracting from 51489440 its reverse (4498415), we obtain a square (46991025 = 6855²).

The spelling of 51489440 in words is "fifty-one million, four hundred eighty-nine thousand, four hundred forty".