51440400 has 240 divisors, whose sum is σ = 200195520. Its totient is φ = 12441600.

The previous prime is 51440393. The next prime is 51440437. The reversal of 51440400 is 404415.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×51440400² = 5292229504320000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 118584 + ... + 119016.

It is an arithmetic number, because the mean of its divisors is an integer number (834148).

Almost surely, 2^51440400 is an apocalyptic number.

51440400 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51440400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100097760).

51440400 is an abundant number, since it is smaller than the sum of its proper divisors (148755120).

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

51440400 is a wasteful number, since it uses less digits than its factorization.

51440400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 471 (or 454 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 51440400 is about 7172.1963163316. The cubic root of 51440400 is about 371.9073650714.

Adding to 51440400 its reverse (404415), we get a palindrome (51844815).

The spelling of 51440400 in words is "fifty-one million, four hundred forty thousand, four hundred".