51240400 has 60 divisors (see below), whose sum is σ = 125479692. Its totient is φ = 20101120.

The previous prime is 51240383. The next prime is 51240407. The reversal of 51240400 is 404215.

It can be written as a sum of positive squares in 6 ways, for example, as 4016016 + 47224384 = 2004^2 + 6872^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51240407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19992 + ... + 22408.

Almost surely, 2^51240400 is an apocalyptic number.

51240400 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 51240400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62739846).

51240400 is an abundant number, since it is smaller than the sum of its proper divisors (74239292).

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

51240400 is a wasteful number, since it uses less digits than its factorization.

51240400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2488 (or 2477 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 51240400 is about 7158.2400071526. The cubic root of 51240400 is about 371.4247477769.

Adding to 51240400 its reverse (404215), we get a palindrome (51644615).

The spelling of 51240400 in words is "fifty-one million, two hundred forty thousand, four hundred".