51216400 has 120 divisors (see below), whose sum is σ = 135616320. Its totient is φ = 18501120.

The previous prime is 51216367. The next prime is 51216401. The reversal of 51216400 is 461215.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (51216401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 174654 + ... + 174946.

It is an arithmetic number, because the mean of its divisors is an integer number (1130136).

Almost surely, 2^51216400 is an apocalyptic number.

51216400 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 51216400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67808160).

51216400 is an abundant number, since it is smaller than the sum of its proper divisors (84399920).

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

51216400 is a wasteful number, since it uses less digits than its factorization.

51216400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353 (or 342 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 51216400 is about 7156.5634210842. The cubic root of 51216400 is about 371.3667493613.

Adding to 51216400 its reverse (461215), we get a palindrome (51677615).

The spelling of 51216400 in words is "fifty-one million, two hundred sixteen thousand, four hundred".